JPS62183033A - Production of magnetic recording body - Google Patents

Abstract

PURPOSE:To improve the durability of a magnetic recording body by forming a protective film on the surface of the thin ferromagnetic metallic film by the plasma polymn. of an organosilicon compound contg. fluorine. CONSTITUTION:A plated layer is formed on a substrate and subjected to post- treatment such as polishing finish and a thin ferromagnetic metallic film is formed on the surface of the layer. The resulting magnetic recording body is set in a plasma polymn. apparatus and vapor of an organosilicon compound contg. fluorine is introduced into the apparatus and plasma-polymerized to form a protective film on the metallic film. A substance represented by a formula SikClHmClnOpFqSrNs (where k=1-4, l=3-16, m=4-30, n=0-5, p=2-5, q=3-20, r=0-5, and s=0-5), e.g., SiC3H4Cl3F3 may be used as the organosilicon compound. By this method, a magnetic recording body having superior durability can be obtd.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method of manufacturing a magnetic recording body using a ferromagnetic metal thin film as a magnetic recording layer, and particularly relates to a method of forming a protective film on the magnetic recording layer. .

[Prior art and its problems]

Magnetic recording materials with a ferromagnetic metal thin film as a magnetic recording layer are produced by vacuum-depositing a ferromagnetic metal material onto a metal disk or tape substrate, or by spin-coding an emulsion in which a ferromagnetic metal material is dispersed in a resin matrix. Manufactured by Although ferromagnetic metal thin films have excellent characteristics for high-density recording, they have drawbacks such as being susceptible to wear and damage due to head contact, and being oxidized in the air, causing changes in characteristics.

For this reason, it has been proposed to improve durability and corrosion resistance by forming a protective film such as carbon on a ferromagnetic metal thin film, but the carbon protective film has some air permeability, making it difficult to improve corrosion resistance. Recently, it has been considered to form a resin protective film using plasma polymerization.

In the conventional formation of a protective film by plasma polymerization, hydrocarbon-based substances are mainly used as monomers. However, the adhesion strength of this protective film to the ferromagnetic metal thin film is insufficient, and CS S (Contact 5tart/
According to evaluations such as 5top) tests, the wear resistance was poor.

c) Means for solving problems and their effects] The present invention has been made to solve the problems of the prior art as described above, and based on the results of various experiments, it has been found that The protective film is
It was discovered that it has excellent durability and uniformity, and was completed.

When the present invention is applied to manufacturing a TRT air disk, the process will be as follows. First, a chemical plating layer such as Ni--P is deposited on an aluminum substrate serving as a base, and after a post-treatment such as polishing is performed, a ferromagnetic metal thin film is formed on the surface by a physical or chemical method. Next, this is sent to a counter electrode type plasma polymerization apparatus as shown in FIG.

In FIG. 1, ■ is a magnetic disk body with a ferromagnetic metal thin film formed on the surface of the base, 2A and 2B are opposing electrodes, and 3
is a Pelger, 4 is a table, 5 is a vacuum pump that vacuums the inside of the Pelger 3, 6 is an absolute vacuum gauge, and 7 is an electrode 2A.
High frequency power supply connected to 2B, 8 monomer gas source, 9
is the carrier gas source and lO is the monomer supply nozzle in the Pelger 3.

Vapor of an organosilicon compound (silicon compound) containing fluorine is introduced into such an apparatus to perform plasma polymerization to form a protective film on the ferromagnetic metal thin film.

The protective film thus obtained has poor durability against head scratching and has high adhesion strength to the ferromagnetic metal thin film. The reason such performance is achieved is that the silicon-containing portion of the monomer molecule polymerizes first and forms a strong bond with the ferromagnetic metal thin film, and the fluorine-containing portion polymerizes later. This is thought to be because it forms the surface layer of the membrane.

The fluorine-containing organosilicon compound used in the present invention has a boiling point observed under normal pressure ranging from 80 to 200'C, and a refractive index at normal temperature and pressure ranging from 1.35 to 1.55. . This compound generally has the following formula: SikCt Ht* CI n○pF,S,N.

The substance used in the present invention can be described in the form k=1
〜4.1=3〜16, m=4〜30, n=0〜
5, p=2~5, q=3~20, r=O~5, S=O~
5. The boiling point under reduced pressure is 3 to 20 mmH.
Entering 90-150 °C under a pressure of g. Specific substances falling within these ranges include S i C* Ha Cl z F s , S i
Ca H? Cl t F s , 5iC4HqOi
FiS, 5iCsHqF*O7, S i Cb H
a F q CI x, S i Cb HI 3 F
302%S i Cb HIjF y Oz
, S i Cq H? CI z F q , S i
C, lH+ s F z○s , SiC, 211
,. F2.81□Ca H+ s F 3 N O, S
i * CIo Hz s F :+ Ot , 5
isC+zHz+FqOz, 51aC+bHz
F+□04.3iC684F+5C1i, 5iCaF
+3H+ff0z, S i C+. Ha F It
CI x, S i CIs H+ x F 1q O
3. S i C+ + Hq Cl z F I ? ,
SiC+tH+*F+t○2, etc.

These are placed alone or mixed with an organic gas such as ethylene, ethane, butane, propane, or butylene, or an inert gas such as argon, helium, or nitrogen in a Pel jar, and the internal pressure is desirably 0.005 to 3 Torr. is 0.
Plasma polymerization is performed between 01 and 1.5 TorrO.

When plasma polymerization is performed using high frequency, the energy density is set at 0.01-4 depending on the high frequency output and the size of the electrode area.
W/am2 is preferably within the range of 0.05 to 3 W/cm2. The output of the high frequency power supply is 30~500W
, preferably maintained between 50 and 250 W, and it is more convenient to perform the heating under as low a power as possible in order to obtain a hard protective film. The high frequency power supply usually has an oscillation frequency of 13.56 MHz and is equipped with a variable capacitance type matching box.

The reaction time of plasma polymerization depends on the type of polymer, flow rate, and electrode arrangement, but usually the desired film thickness can be obtained preferably in 10 seconds to 10 minutes, and more preferably in 30 seconds to 3 minutes. Select equipment conditions and monomer conditions accordingly.

The thickness of the polymer film thus obtained is usually between 10 and 1000. Particularly preferably, it is distributed among 80 to 600 people. If the film thickness is too thin, durability and corrosion resistance cannot be obtained. On the other hand, if the film is too thick, spacing loss increases, which adversely affects recording and reading characteristics.

The temperature of the magnetic disk body has a large effect on film growth. Lower temperatures can increase the growth rate of the film, and the surface temperature of the ferromagnetic metal thin film is preferably 50 to 10
It is kept at 0'C.

When introducing monomers, it is desirable to introduce four high-boiling point monomers using heating piping.

It is desirable to minimize the variation in the thickness of the polymerized film, and to achieve this, it is effective to rotate or vibrate the magnetic disk body during plasma polymerization, or to move the electrodes at a constant speed. be.

High frequency devices for plasma polymerization include inductance type and capacitance type, and a protective film can be formed using either device.

Although the present invention is mainly suitable for manufacturing magnetic disks, it is equally applicable to manufacturing other magnetic recording media such as magnetic tapes, floppy disks, magnetic cards, etc.

〔Example〕

Diameter 5! using the opposite electrode type plasma polymerization apparatus shown in Figure 1!
A protective film was formed on the surface of the main body of the magnetic disk by plasma polymerization. Stainless steel electrodes with a diameter of 130 mm were used, and the distance between the electrodes was kept at 25 mm. The frequency of the high frequency power supply is 13.56 MHz, and the supplied power is 100 MHz.
W (reflected power 1.5 W).

3,3,3-trifluoropropyltetrachlorosilane was supplied as a monomer at a rate of 60 cc/min under heating at 55°C, and pure argon was supplied as a carrier gas at a rate of 8 cc/min.
It was supplied under heating at 0°C. The pressure inside the Herjar is 0.1
Torr.

Various film thicknesses were obtained by changing the reaction time, and the film thicknesses were measured using a stylus-type film thickness measuring device. Both protective films were uniform and free of pinholes.

Further, the C8S cycle of the obtained magnetic disk was measured using a C8S tester.

The above results are shown in Table 1. As a comparative example, the C8S characteristics of a magnetic disk coated with a hydrocarbon protective film obtained by plasma polymerizing ethylene and a magnetic disk coated with a carbon protective film are also shown.

According to the method of the present invention, although the protective film is formed by plasma polymerization, it is possible to obtain C8S durability almost equivalent to that of a carbon protective film.

Table 1 [Effects of the Invention] As explained above, according to the present invention, durability is improved by using a fluorine-containing organosilicon compound as a monomer when forming a protective film on a ferromagnetic metal thin film by plasma polymerization. A magnetic recording medium with excellent properties can be manufactured.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a plasma polymerization apparatus used in the present invention. l-Magnetic disk body, 2A/2B-electrode, 3-perzier, 4-table, 5-vacuum pump, 6-absolute vacuum gauge, 7-high frequency power supply, 8-monomer gas source, 9-carrier gas source, 10-monomer supply nozzle.

Claims (1)

[Claims] A ferromagnetic metal thin film is formed on a substrate, the ferromagnetic metal thin film is exposed to a monomer vapor of a fluorine-containing organosilicon compound to perform plasma polymerization, and a protective film of the above compound is formed on the surface of the ferromagnetic metal thin film by plasma polymerization. A method of manufacturing a magnetic recording body, the method comprising: forming a magnetic recording body;