JPS61216123A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve sufficiently the resistance to abrasion and corrosion of the titled medium by increasing the flow rate of a gaseous monomer or decreasing high-frequency electric power to carry out plasma polymerization and forming a plasma-polymerized protective layer of an org. compd. whose degree of corss-linking decreases as the distance from the surface decreases on a ferromagnetic metallic thin film layer. CONSTITUTION:A substrate 1 moving along the peripheral side surface of a cylindrical can 5 is successively exposed in each compartment A, B and C to the same gaseous monomer of an org. compd. from gas introducing pipes 19, 20 and 21. Accordingly, the flow rate of the gaseous monomer is successively increased in each compartment A, B and C or the high-frequency wave impressed on electrodes 22, 23 and 24 is reduced to carry out plasma polymerization. Consequently, a plasma-polymerized protective layer 29 of an org. compd. whose degree of corss-linking is reduced as the distance from the surface is decreased, whose surface energy is low, which hardly absorbs oxygen and a hydroxyl group, whose degree of cross-linking is high at the interface with a ferromagnetic metallic this film layer 28 and having an excellent adhesive property is formed on the ferromagnetic metallic thin film layer 28 which is formed on the substrate 1.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer, and more specifically relates to a method for producing a magnetic recording medium having a magnetic recording layer having a ferromagnetic metal thin film layer, and more specifically, the present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer. The present invention relates to a method for manufacturing a recording medium.

[Conventional technology]

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film layer is
It is usually made by depositing metals or their alloys on a base film by vacuum deposition, etc., and has characteristics suitable for high-density recording, but on the other hand, it has a high coefficient of friction with the magnetic head, making it susceptible to wear and damage. It also has disadvantages such as gradual oxidation in the air and deterioration of magnetic properties such as maximum magnetic flux density.

For this reason, durability has been conventionally improved by providing various protective film layers on the ferromagnetic metal thin film layer. For example, using a plasma processing apparatus as shown in FIG. A polyester film 1 having a ferromagnetic metal thin film formed on its surface is moved from a raw roll 3 in a vacuum chamber 2 through a guide roll 4 along the circumferential side of a cylindrical can 5, and then through a guide roll 6. The interior of the vacuum chamber 2 is maintained at a predetermined degree of vacuum by the exhaust system 8, and the organic compound 1' is fed from the gas introduction pipe 9 attached to the vacuum chamber 2.
- Introducing ``7'' 6. Applying electric 11'' high frequency with high frequency power source 10 to plasma polymerize, ferromagnetic metal thin:
1FIiiiiii&m*[(li@1Ic7)7”5
-Xq*1MmWH'AM@□ 1 is being provided.

□ : [Problem that the invention seeks to solve]
・1 However, with this method, the plasma-polymerized protective film layer of the organic compound 1 that is deposited and formed can be formed by reducing the amount of monomer gas introduced during film formation.
When high frequency power is increased by 1 to increase the adhesion with the ferromagnetic metal thin film layer and improve wear resistance, the surface energy of the protective film layer decreases by 1.
As a result, a good anticorrosion effect cannot be obtained, and
When the amount of monomer gas introduced is increased and the high frequency power is decreased, there are problems such as a decrease in adhesiveness and strength of the film.

[Means for solving problems]

This invention was developed as a result of various studies in view of the current situation.
A ferromagnetic metal thin film layer made of a metal or an alloy thereof is formed on a substrate, and then the substrate on which this ferromagnetic metal thin film layer is formed is placed in two or more compartments in a vacuum chamber and straddled between each compartment. The substrate is set in a plasma processing apparatus equipped with a cylindrical can with an exposed circumferential surface and a plasma generation electrode disposed in each compartment facing the substrate that moves along the circumferential surface of the cylindrical can. While moving along the circumferential side of the cylindrical can, monomer gas of the same organic compound is introduced into each compartment, and the compartments are sequentially divided from the compartment where the substrate is introduced to the compartment where the substrate is taken out. When plasma polymerization is performed by increasing the gas flow rate of the monomer gas in the room or by lowering the radio frequency power, the degree of crosslinking decreases toward the surface of the ferromagnetic metal thin film layer, and the surface energy decreases, and the ferromagnetic metal thin film Odor near the interface with the layer: 1
7. A magnetic recording medium with sufficiently improved abrasion resistance and corrosion resistance is obtained by forming a plasma polymerized protective film layer of an organic compound with a high degree of crosslinking and excellent adhesiveness.1'''-'bly゛'Q゛f&8h
t:'j>(DT:~.

1 Hereinafter, this invention will be explained with reference to the drawings.

1 □21. ．． . (7) Q! ]”r(□□wa,,
Off □□; This plasma processing apparatus has 1, a raw roll 3, a guide roll 4, and a 'P1ffi' in a vacuum chamber 2.
4J'? ”-t-75, ka, il, .-7,6 and j
-Yo.

It is different from the conventional printer 1 shown in Fig. 1 in that the roll 7 is provided.
Although it is the same as the Razz processing equipment, the inside of the vacuum chamber 2 is divided into sections by walls 12, 13, 14, and 15 to provide compartments iA, B, and C, and an exhaust system 16, 19 is provided for each compartment. 7.18
and gas inlet pipe 19.20.21] 2, 6 yo 6
6o cylinder 1 size, 2. . Zhou, 11 6o, 091]
Katokao I LZ'1friilL"'C@m
22.23.24 and 1, connect to each high frequency power source 25.26.27 and connect it to each high frequency power source 25.26.27.
W&'nee yo h4;t:, the base body 1 moving along the circumferential side of the cylindrical can 5 is introduced into each compartment A, B, C sequentially from the gas inlet pipes 19, 20, 21 respectively. Exposure to monomer gas of organic compounds. Therefore, the gas flow rate of the monomer gas should be increased in the order of each compartment A, BXC, or each electrode 2 should be increased in the order of each compartment A, B, and C.
2.23.24 If plasma polymerization is performed by reducing the high frequency applied to A plasma-polymerized protective film layer of an organic compound that absorbs oxygen, hydroxyl groups, etc., and has a high degree of crosslinking and excellent adhesiveness near the interface with the ferromagnetic metal thin film layer is formed.

As a result, a plasma polymerized protective film layer with good adhesion and excellent corrosion resistance is formed on the ferromagnetic metal thin film layer on the substrate l, and a magnetic recording medium with sufficiently improved wear resistance and corrosion resistance is obtained. .

The organic compound monomer gases introduced into the compartments A, B, and C in the vacuum chamber 2 from the gas introduction pipes 19, 20, and 21 include, for example, C2F4,
[C3Fs, etc.] Monomer gas of non-atomic organic compounds, monomer gas of hydrocarbon compounds such as propane, ethylene, propylene, etc., and silicon-based organic compounds such as tetramethylsilane, octamethylcyclotetrasiloxane, hexamethyldisilazane, etc. A monomer gas or the like is preferably used, and when plasma polymerization is performed in the monomer gas of these organic compounds by applying high frequency waves to each of the plasma generating electrodes 22, 23 and 24, radicals are generated, and the generated radicals are It reacts and polymerizes to form a film. The radicals used in such plasma polymerization are those in which these organic compounds have double bonds or triple bonds, metal salt compounds with a metal element at the end, or O
The more functional groups such as H groups, the easier it is to form, so those having these unsaturated bonds, metal elements, functional groups, etc. are more preferably used. Also, when plasma polymerizing these monomer gases, if a carrier gas such as argon gas, helium gas, or oxygen gas is present, the monomer gases will be deposited at a rate 3 to 5 times faster than when plasma polymerizing them alone. It is preferable to use these carrier gases together. When coexisting with these carrier gases, it is preferable that the composition ratio of the carrier gas to the monomer gas of the organic compound be within the range of 1:1 to 20:1. If the carrier gas is too small, precipitation may occur. If the amount is too high, the monomer gas will decrease and the plasma polymerization reaction will be hindered. Note that when using a monomer gas of a hydrocarbon compound, it is not preferable to use oxygen gas as a carrier gas because an oxidation reaction will occur if oxygen gas is used as a carrier gas.

In this way, the gas flow rate and high-frequency power when plasma polymerization is performed by introducing monomer gas of an organic compound into each compartment A, B, and C from each gas introduction pipe 19, 20, and 21 are different for each compartment. , along the moving direction of the substrate 1 moving along the circumferential side of the cylindrical can 5, the compartments A, B,
It is necessary to increase the gas flow rate and the high frequency power in the order of C, but the higher the gas flow rate, the faster the deposition rate, but on the other hand, the monomer gas with a relatively low molecular weight is plasma polymerized and a hard protective film layer is obtained. Also, if the gas flow rate is reduced and the high frequency power is increased, the deposition rate will be slowed down, but at the same time a relatively hard protective film layer made of polymer will be obtained.
If the gas flow rate is reduced and the high frequency power is increased too high, the monomer gas will turn into powder and a plasma polymerized protective film layer will not be formed. 3W/cJ
It is preferable to set the gas flow rate within the range of 10 to 300
secm, and the high frequency power is 0.05 to 2 W/c.
It is more preferable to set it within the range of J.

In this way, organic compound monomer gas is introduced into each of the compartments A, B, and C, and the gas flow rate is increased or the high frequency power is decreased in order to form an organic compound plasma that is precipitated by plasma polymerization. The polymerized protective film layer has a lower degree of crosslinking and lower surface energy as it approaches the surface, and a higher degree of crosslinking near the interface with the ferromagnetic metal thin film layer, resulting in a dense layer with excellent adhesive properties. A magnetic recording medium with sufficiently improved corrosion resistance and durability can be obtained. Note that the number of compartments is not limited to three as in the above embodiment, and an appropriate number of compartments of two or more may be provided as necessary.

The formation of the ferromagnetic metal thin film layer on the substrate is performed using Co, Fe,
%N 1% CON i alloy, Co-Cr alloy, C
This is accomplished by depositing a ferromagnetic material such as an o-P alloy or a Co-N1-P alloy onto a substrate by means such as vacuum evaporation, ion blasting, sputtering, or plating.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of 10 μm was loaded into a vacuum evaporation apparatus, and cobalt was heated and evaporated under a residual gas pressure of 5×10 −5 torr of oxygen gas to deposit a 100 μm thick cobalt film on the polyester film. A magnetic metal thin film layer was formed. Next, using the plasma processing apparatus shown in FIG.
It was moved along the circumferential side of the cylindrical can 5 through the guide roll 6, and set so as to be wound onto the winding roll 7 through the guide roll 6. Next, add polyester film 1 to 5
Each compartment A, B, C while running at a speed of m/min.
50sec, 150sccm, 250sc of C2F4 gas from each gas introduction pipe 19, 20, 21 respectively.
C2F4 gas was introduced at a flow rate of cm, and the gas pressure of C2F4 gas was set to 0.05 Torr in each compartment, 0.1 Torr in compartment B, and 0.5 Torr in compartment C, and each plasma generation electrode 22.23 Plasma polymerization was carried out with the high frequency power of .24 constant at 0.5 W/cn+. The thickness of the plasma polymerized protective film layer formed at this time was 100 layers. Thereafter, it was cut to a predetermined rIJ, and a magnetic tape A was prepared in which a ferromagnetic metal thin film layer 28 and a plasma polymerized protective film layer 29 were laminated on a polyester film 1 as shown in FIG.

, '"112: In the plasma polymerization of Example 1,
The flow rate of 02F4 gas introduced into each compartment A, B, C is 1
50 seconds, the gas pressure of C2F4 gas in each compartment was kept constant at 0.1 Torr, and the high frequency power of each plasma generation electrode 22, 23, 24 was set to 0.1 Torr.
IW/crA in compartment B, 0.6W/cJ in compartment B, compartment C
Except that plasma polymerization was performed at 0.2 W/cJ at
Plasma polymerization was carried out in the same manner as in Example 1 to produce a magnetic tape.

Comparative Example 1 In the plasma polymerization of Example 1, each compartment A, B, C
The flow rate of the 02F4 gas introduced into the chamber was set to 50 seconds, and the gas pressure of the C2F4 gas in each compartment was set to 0.05 seconds.
) - Plasma polymerization was carried out in the same manner as in Example 1, except that the plasma polymerization was carried out at a constant value, and a magnetic tape was produced.

Comparative Example 2 In the plasma polymerization of Example 2, the high frequency power was set to 0.2
A magnetic tape was produced by plasma polymerization in the same manner as in Example 2, except that the plasma polymerization was carried out at a constant W/c♂.

↓ Comparative Example 3: A magnetic tape was produced in the same manner as in Example 1 except that the formation of the plasma polymerized protective film layer was omitted.

Magnetic tape 4 obtained in each example and each comparative example
Adhesion, abrasion resistance and corrosion resistance were tested. The adhesion test was performed using a tensile tester with 90 degree peeling.
The peel adhesion strength was measured using a method. In addition, the wear resistance A purity test was performed by performing a sliding test using a sliding tester and measuring the number of times the ferromagnetic metal thin film layer surface was scratched. The obtained magnetic flux density was measured by leaving the tape under the conditions of 60°C and 90% RH for 70 minutes, and comparing it with the maximum magnetic flux density of the magnetic tape before leaving it as 100%. The deterioration rate was investigated based on the value.

1. The table below shows the results.

” ・) As is clear from the table above, the magnetic tapes obtained by the present invention (Examples 1 and 2) were all similar to Comparative Examples 1 to 3.
Compared to the magnetic tape obtained by the present invention, the adhesive force is greater, the number of times of sliding is greater, and the rate of deterioration is lower. Therefore, the magnetic recording medium obtained by the present invention has a lower degree of crosslinking toward the surface, and has better wettability. It can be seen that the abrasion resistance and corrosion resistance are further improved as a result of the formation of a plasma-polymerized protective film layer which has a low cross-linking rate and a high degree of cross-linking near the interface and has excellent adhesion.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a conventional plasma processing apparatus, and FIG. 2 is a schematic sectional view of a plasma processing apparatus used in the manufacturing method of the present invention.
A schematic sectional view showing an example, and FIG. 3 is a partially enlarged sectional view of a magnetic tape obtained by the present invention. ■... Base body, 2... Vacuum chamber, 5... Cylindrical can, 12.13, 14.15... Partition wall, 16, 17.1
8...Exhaust system, 19,20.21...Gas introduction pipe,
22.23.24... Electrode, 28... Ferromagnetic metal thin film layer, 29... Plasma polymerized protective film layer, A, B, C.
・Compartment room

Claims (1)

[Claims] 1. A ferromagnetic metal thin film layer made of metal or an alloy thereof is formed on a substrate, and then the substrate on which this ferromagnetic metal thin film layer is formed is placed in two or more compartments and each compartment in a vacuum chamber. It is set in a plasma processing apparatus equipped with a cylindrical can whose circumferential side is exposed across the cylindrical can and a plasma generation electrode disposed in each compartment facing a substrate that moves along the circumferential side of the cylindrical can, The substrate is moved along the circumferential side of the cylindrical can, and monomer gas of the same organic compound is introduced into each compartment, sequentially from the compartment where the substrate is introduced to the compartment where the substrate is taken out. Plasma polymerization is performed by increasing the gas flow rate of the monomer gas in the compartment or by lowering the radio frequency power to form a plasma polymerized protective film layer of an organic compound with a degree of crosslinking decreasing toward the surface on the ferromagnetic metal thin film layer. A method for manufacturing a magnetic recording medium characterized by: