JPS61122924A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a durable recording medium having a protective layer which is dense and tough and has a small coefft. of friction by providing a plasma-polymerized protective layer consisting of a silicon org. compd. contg. at least Si and O on a magnetic layer while controlling the atomic number ratio of Si and O to a specific range. CONSTITUTION:A thin ferromagnetic metallic film layer 10 is formed on a base body 1 consisting of a polyeser film or the like and thereafter a mixture composed of the silicon org. compd. such as tetramethyl silane and gaseous O2 is introduced through a gas introducing pipe 6 or the silicon org. compd. contg. Si and O is introduced into a plasma treating vessel 2 while the base body 1 with the thin magnetic film 5 faced on the outside is moved along a cylindrical can 4 from a roll 3 in said vessel toward a take-up roll 5 to form the plasma-polymerized protective layer 11 on the film 10 by an electrode 7. The O atomic number ratio with respect to the Si atomic number of the film 11 is controlled within a 0.7-1.3 times range. The protective layer 11 having 0.7-1.3 times O/Si by the atomic number ratio and N/Si in a 0.3-0.7 times range is provided by using the org. compd. contg. Si, O and N. The magnetic recording medium having the excellent runnability, durability, etc. is thus obtd.

Description

[Detailed description of the invention] [Industrial field of application and purpose of the invention] The present invention relates to a magnetic recording medium and a method for manufacturing the same, and an object of the present invention is to provide a magnetic recording medium with excellent durability and runnability. .

[Conventional technology]

Generally, magnetic recording media are made by depositing magnetic powder together with a binder component on a base film, or by depositing ferromagnetic metals or their alloys on a base film by vacuum deposition or the like.

The magnetic layer is likely to be worn out due to violent sliding contact with a magnetic head during recording and reproduction, especially in ferromagnetic metal thin film type magnetic recording media formed by vacuum deposition.

Although it has excellent high-density recording characteristics, it has drawbacks such as a high coefficient of friction with the magnetic head, making it susceptible to wear and damage, and uneven running when the tape runs.

For this reason, various protective film layers are provided on the AI magnetic layer to improve durability and runnability. In recent years, for example, octamethylcyclotetrasiloxane has been subjected to plasma polymerization.

It has been proposed to form a plasma-polymerized protective film layer of a silicon-based organic compound on a magnetic layer [Tetsuo Iijima, Hiroaki Hanabusa, Journal of the Institute of Electronics and Communication Engineers, J67-C, No. 1 (1984)]. However, when plasma polymerization is performed using this type of monomer gas of octamethylcyclotetrasiloxane, because of its high oxygen content, it reacts in the gas phase and turns into powder, and octamethylcyclotetrasiloxane decomposes. 510M! Due to the formation of a film, it is not possible to obtain a plasma polymerized protective film layer of a silicon-based organic compound that is sufficiently dense, strong, and has a small coefficient of friction, and it is still not possible to sufficiently improve durability and runnability.

[Means for solving problems]

The present invention was developed in view of the current situation, and a plasma polymerized protective film layer of a silicon-based organic compound containing at least silicon and oxygen is provided on the magnetic layer.

The present invention is characterized in that the amount of oxygen atoms relative to the amount of silicon atoms in the plasma polymerized protective film layer is regulated within a range of 0.7 to 1.3 times in terms of atomic ratio.
The magnetic layer formed on the substrate is exposed to a plasma of at least a silicon-based organic compound monomer gas alone or a mixed gas of a silicon-based organic compound monomer gas and oxygen gas, and plasma polymerization is performed to form silicon containing at least oxygen. A plasma polymerized protective film layer of organic compounds is formed, and the plasma polymerization is maintained. It is characterized in that the atomic ratio of the oxygen atomic weight to the silicon atomic weight in the film layer is regulated within a range of 0.7 to 1.3 times.

Furthermore, the present invention provides plasma polymerization protection EIi of a silicon-based organic compound containing at least silicon, oxygen, and nitrogen on the magnetic layer.
A JIII layer in which the oxygen atomic weight and nitrogen syK molecular weight are 0.7 to 1.3 times and 0.3 to 0.7 times the silicon atomic weight in the plasma polymerized protective film layer in terms of atomic ratio.
It is characterized by being regulated by +.

Furthermore, the present invention provides a magnetic layer formed on a substrate in a plasma of a monomer gas of a silicon-based organic compound containing at least silicon and nitrogen or a mixed gas of a silicon-based organic compound monomer gas and oxygen gas. is exposed and subjected to plasma polymerization to obtain at least rI! A plasma-polymerized protective film layer of a silicon-based organic compound containing element and nitrogen is formed, and the atomic ratio of the acid S atomic weight and the nitrogen l/I# atomic weight to the silicon atomic weight in the plasma-polymerized image 11 [111] is 0. 7-1.3 times and 0.3-0.
It is characterized by being regulated within a seven-fold range.

In the present invention, the plasma polymerization performed during the formation of a plasma polymerized protective film layer on the magnetic layer includes silicon atoms, silicon atoms and nitrogen atoms, silicon atoms, nitrogen atoms and carbon atoms,
Alternatively, a monomer gas of a silicon-based organic compound containing silicon atoms, nitrogen atoms, carbon atoms, and hydrogen atoms is mixed with a trace amount of oxygen gas at a volume ratio of 10 to 30% by volume to this monomer gas as a carrier gas, and this mixed gas is carried out by plasma polymerization using high frequency waves.

Since a very small amount of oxygen gas is also used as a carrier gas, as in the case of plasma polymerization using monomer gas of octamethylcyclotetrasiloxane, the monomer is The gas does not react in the gas phase and turn into powder or form a SiO film, and the atomic ratio of silicon atoms to oxygen atoms is 0.7 to 1.3 times. From 0.
7 times nitrogen atoms, or 0.7 times to 1.3 times oxygen atoms and 0.3 times to 0.7 times nitrogen atoms and 1.5 times to 3 times
．． Plasma polymerization of dense and tough silicon-based organic compounds containing 5 times as many carbon atoms! A fil1 layer is formed, and durability and runnability are sufficiently improved. Furthermore, the small amount of aSS particles contained in the plasma polymerized protective film layer improves the adhesion with the magnetic layer, further improving the durability. Further, by mixing oxygen gas with the monomer gas mentioned above, the oxygen atom content can be easily adjusted.

Plasma polymerization of such silicon-based organic compounds 1! As the silicon-based organic compound monomer gas used to form the film layer, for example, silicon-based organic compound monomer gas such as tetramethylsilane, vinyltrimethylsilane, trimethylsilylacetylene, etc. is preferably used. Radicals are generated from these silicon-based organic compound gases by high frequency, and the generated radicals react and polymerize to form a film.

In addition, when plasma polymerizing the monomer gas of these silicon-based organic compounds, the oxygen gas mixed and used as a carrier gas is 10 to 30% by volume of the monomer gas of these silicon-based organic compounds. It is preferable to use it within the range of . If the amount is too high, the monomer gas of the silicon-based organic compound will react in the gas phase and turn into powder, or the silicon-based organic compound will decompose and form a SiO film, resulting in a dense and tough plasma polymerized protective film layer of the silicon-based organic compound. is not obtained. In this way, when oxygen gas is mixed in a volume ratio of 10 to 30% by volume with respect to the monomer gas of a silicon-based organic compound, and plasma polymerization is performed using this, the number of atoms is A plasma-polymerized protective film layer of a dense and tough silicon-based organic compound containing 0.7 to 1.3 times as many oxygen atoms is formed, and the minute amount of oxygen atoms contained in this plasma-polymerized protective film layer makes it magnetic. The adhesion with the layer is also improved, and the abrasion resistance and runnability are further improved. 6 When performing plasma polymerization, the gas pressure of the mixed gas of the silicon-based organic compound 7-mer gas and oxygen gas and the high frequency The higher the gas pressure, the faster the deposition speed, but the monomer gas has a relatively low molecular weight and is plasma polymerized, making it difficult to obtain a hard protective film layer. Although the speed is slow, a relatively hard protective film layer made of polymer can be obtained, but if the gas pressure is low and the high frequency output is too high, the monomer gas will turn into powder and a plasma polymerized protective film layer will not be formed. . Therefore, the gas pressure is set in the range of 0.005 to 0.30 Torr, and the high frequency output is set in the range of 0.1 to 2. It is preferable that the range is OW/c+J, the gas pressure is 0.01 to 0.1 Torr, and the high frequency output is 0.3 to 1. More preferably, the range is OW/Cl1l.

The film thickness of such a plasma-polymerized protective film layer of a silicon-based organic compound deposited by plasma polymerization is 20 to 20 cm.
The thickness is preferably within the range of L000. If the film thickness is too thin, the durability and runnability effects of this protective film layer will not be sufficiently exhibited.

If it is too thick, the spacing loss will be too large! Adversely affects magnetic conversion characteristics.

The magnetic layer formed on the substrate contains γ-FezOs powder + FazO- powder, Go-containing? Fe=Ot powder-Co
Contains Fe s Oa powder, FsPB powder, CO powder, F
Magnetic powder such as e-Ni powder is coated on a substrate together with a binder component and an organic solvent and dried, or Go
, Ni, Fs-Go-Ni.

Ferromagnetic materials such as Co-Cr, Go-P, Go-Ni-P are deposited by vacuum evaporation, ion blasting, sputtering,
It is formed by depositing it on the substrate by means such as plating.

Further, the magnetic recording medium includes various types of structures that come into sliding contact with a magnetic head, such as a magnetic tape having a synthetic resin film such as a polyester film as a base, a magnetic disk or a magnetic drum having a disk or drum as a base.

〔Example〕

Next, examples of the present 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 vacuum of 5
A ferromagnetic metal thin film layer made of cobalt was formed.

Next, using the plasma processing apparatus shown in FIG. 1, the polyester film 1 with the ferromagnetic metal thin film layer formed thereon is passed from the raw roll 3 to the circumferential side of the cylindrical can 4 at 1 m/min in the processing tank 2. The winding roll 5 is moved at a speed of
I set it so that it would be wound up. At the same time, monomer gas of tetramethylsilane was introduced from the gas introduction pipe 6 at a flow rate of 50 sccm, and the electrode 7 was used at a gas pressure of 0.024 Torr.
A high frequency of 3.56 MHz was applied at an output of tsow to form a plasma polymerized protective film layer.

Thereafter, it was cut to a predetermined width to produce a magnetic tape A in which a ferromagnetic metal thin film layer 10 and a plasma polymerized protective film II [11] were sequentially laminated on a polyester film L as shown in FIG. . The thickness of the plasma polymerized protective film layer at this time was 220. In addition, as a result of examining the ratio of the number of atoms of component elements in the plasma polymerized protective film layer using an Auger electron spectrometer, we found that the number of silicon atoms versus carbon f3
The number of atoms to the number of oxygen atoms was 1:2.81:1°11. In the figure, 8 is an exhaust system for reducing the pressure inside the processing tank l, and 9 is an exhaust system for reducing the pressure inside the processing tank l. This is a high frequency power source for applying high frequency to the pole 7.

Example 2 Plasma polymerization protection lIg in Example 1! In the formation of a, instead of the monomer gas of tetramethylsilane,
Magnetic tape A was prepared in the same manner as in Example 1 except that the same amount of vinyltrimethylsilane monomer gas was used.
The thickness of the plasma polymerized protective film layer at this time was 230 layers. In addition, as a result of examining the ratio of the number of atoms of component elements in the plasma polymerized protective film layer using an Auger electron spectrometer, the number of silicon atoms to the number of carbon atoms to the number of oxygen atoms was 1 to 3.
．． The ratio was 06 to 1.07.

Example 3 Plasma polymerization retention ml in Example 1! $7! In forming t, the amount of oxygen gas introduced was changed from 12 sec+m to 6 sec+m.
Magnetic tape A was produced in the same manner as in Example 1 except that the gas pressure was changed to 0.022 torr and the gas pressure was changed to 0.022 torr.

The thickness of the plasma polymerized protective film layer at this time was 200 mm. In addition, as a result of checking the ratio of the number of atoms of the component elements in one polymeric protective film layer using an Auger electron spectrometer, the number of silicon atoms to the number of carbon atoms to the number of oxygen atoms was 1:3.42:0.
．． It was 67.

Example 4 In the formation of the plasma polymer N film layer in Example [, the amount of oxygen gas introduced was changed from 12 sccm to 20 sec.
Change to 2. Magnetic tape A was prepared in the same manner as in Example I except that the gas pressure was 0.026 Torr. The thickness of the plasma polymerized protective film layer at this time was 230.
Ivy 6 again. Plasma polymerization protection! ! ! As a result of examining the ratio of the number of component element atoms in the calendar using an Auger electron spectrometer, the number of silicon atoms to the number of carbon atoms to the number of oxygen atoms is 1 to 2.
．． It was 21 to l, 31.

Example 5 α-F+! Magnetic powder 600 parts by weight Eslec CN (manufactured by Block Chemical Industry Co., Ltd. 8Qn, monophonic vinyl-vinyl acetate copolymer) Bandex T-5250 (large 30 parts by weight, manufactured by Nippon Ink Co., Ltd., urethane elastomer) Coronate Japan Polyurethane 10 parts (manufactured by Kogyo Co., Ltd., trifunctional low molecular weight isocyanate compound) Methyl isobutyl ketone 400 sr toluene 400 This composition was mixed and dispersed in a ball mill for 72 hours, and the magnetic paint was coated on a 10 μm thick polyester film with a dry thickness of 4 μm. Apply and dry.

A magnetic layer was formed. In Step 1-1, a plasma polymerized protective film layer was formed in the same manner as in Example 1 to prepare magnetic tape A.

Comparative Example 1 In the formation of the plasma polymerized protective film layer in Example 1, 50 seconds of octamethylcyclotetraxane was used instead of tetramethylsilane, the addition of oxygen gas was omitted, and the gas pressure was set to 0.02 Torr. A magnetic tape was produced in the same manner as in Example 1 except for this. The thickness of the plasma polymerized protective film layer at this time was 300. In addition, as a result of examining the ratio of the number of component light S atoms in the plasma polymerized protective film layer using an Auger electron spectrometer, the ratio of silicon atoms to carbon atoms to oxygen atoms was 1:1, and 75:1.81. Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1, except that in the formation of the plasma polymerized protective film layer in Example 1, the addition of oxygen gas was omitted and the gas pressure was set to 0.02 Torr. The thickness of the plasma polymerized protective film layer at this time was 230 layers.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 2, except that in the formation of the plasma polymerized protective film layer in Example 2, the addition of oxygen gas was omitted and the gas pressure was set to 0.02 Torr.

The thickness of the plasma polymerized protective film layer at this time was 240.

Comparative Example 4 In Example J, 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 obtained in each of Examples 1 to 5 and Comparative Examples 1 to 4 The tape was tested for durability and runnability. Durability was tested by subjecting the obtained magnetic tape to a still test using a VH8 type VTR and measuring the number of times until the plasma polymerized protective film layer was scratched. Running performance is VH3
The tape tension on the take-up side during running on a type VTR was measured, and the degree of friction between the magnetic tape and the magnetic head was tested. The results are shown in Table 1.

Table 1 Example 6 A polyester film with a thickness of 10 μm was loaded into a vacuum evaporation apparatus, and Kobal 1- was heated and evaporated under a vacuum of 5×10-'hr to form a 1000-μm-thick polyester film on the polyester film.
A ferromagnetic metal thin film layer made of cobalt was formed.

Next, a plasma processing apparatus shown in FIG. 1 was used.

The polyester film 1 on which the ferromagnetic full FF1J film layer is formed is moved from the raw roll 3 along the circumferential side of the cylindrical can 4 at a speed of 1 m/min in a process R1462, and is wound onto a take-up roll 5. I set it to At the same time, a monomer gas of hexamethyldisilazane was introduced from the gas introduction pipe 6 at a flow rate of 50 sccm, and oxygen gas was introduced as a carrier gas at a rate of 12 seconds, so that the gas pressure was 0.
A high frequency of 13.56 MHz was applied from the pole 7 at an output of tsow at 0.024 torr to form a plasma polymerized protective film layer.

Thereafter, it was cut to a predetermined width to produce magnetic tape A. The thickness of the plasma polymerized protective film layer at this time was 300. In addition, as a result of examining the ratio of the number of atoms of component elements in the plasma polymerized protective film layer using an Auger electron spectrometer, we found that the number of silicon atoms, the number of carbon atoms, the number of nitrogen atoms, and the acid s
The number of yK offspring was ■ vs. 2.54 vs. 0.47 vs. 1.06.

Example 7 In the formation of the plasma polymerized protective film in Example 6,
Magnetic tape 8 was prepared in the same manner as in Example 1 except that the same amount of monomer gas of tetramethyldisilazane was used in place of the monomer gas of hexamethyldisilazane. 6 The thickness of the plasma polymerized protective film layer at this time was There were 270 people4
Also. As a result of examining the ratio of the number of atoms of the component elements in the plasma polymerized protective film 1 using a dimension-die electron spectrometer, the number of silicon atoms versus the number of carbon atoms versus the number of nitrogen atoms versus the number of oxygen atoms is as follows.
The ratio was 1:1.67:0.54:1.21.

Example 8 In forming the plasma polymerized image 'RIII layer in Example 6, the amount of oxygen gas introduced was changed from 12 sc, cm to ls
Except that it was changed to ccm and the gas pressure was set to Q, 022 Torr.

Implementation (Magnetic tape A was made in the same way as ft1 spirit.

The thickness of the plasma polymerized protective film layer at this time was 300. In addition, as a result of examining the ratio of the number of atoms of component elements in the plasma polymerized protective film layer using an Auger electron spectrometer, the number of silicon atoms to the number of carbon atoms to the number of nitrogen atoms to the number of oxygen atoms was 1:3.21:0. The ratio was .61 to .77.

Example 9 In the formation of a plasma polymerized protective film layer in actual *fff6, the amount of oxygen gas introduced was changed from 12 sc + w to 20 sc
Magnetic tape A was produced in the same manner as in Example 1, except that the gas pressure was changed to cm and the gas pressure was set to 0.026 torr. The thickness of the plasma polymerized image S film layer at this time was 280. In addition, as a result of examining the ratio of the number of atoms of component elements in the plasma polymerized protective film layer using an Auger electron spectrometer,
The number of silicon atoms versus the number of carbon atoms versus the number of nitrogen atoms versus the number of oxygen atoms was l versus 2.06 versus 0.32 versus 1.29.

Example IO α-Fe magnetic powder 600 parts by weight Eslec CN (manufactured by Tanemizu Kagaku Kogyo 80, vinyl chloride-vinyl acetate copolymer) Bandex T-5250 (large 30 ft, manufactured by Nippon Ink Co., Ltd., urethane elastomer) Coronate Trifunctional low molecular weight isocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd.) Methyl isobutyl ketone (400 n) Toluene (400 parts by weight) This composition was mixed and dispersed in a ball mill for 72 hours, and the magnetic paint was coated on a 10 μm thick polyester film. A magnetic layer was formed by coating and drying to a dry thickness of 4 μm. Then,
A plasma polymerized protective film layer was formed on this in the same manner as in Example 1 to produce magnetic tape A.

Comparative Example 5 In the formation of the plasma polymerized protective film layer in Example 6, 50 seconds of octamethylcyclotetraxane was used instead of tetramethylsilane, addition of oxygen gas was omitted, and the gas pressure was set to 0.02 Torr. is implemented g41
I made magnetic tape in the same way. The thickness of the plasma polymerized protective film layer at this time was 300. In addition, as a result of examining the ratio of the number of atoms of the component elements in the plasma-polymerized tfiFeA layer using an Auger electron spectrometer, the number of silicon atoms vs. the number of carbon atoms vs. the number of IRH atoms, 1
vs. 1, 75 vs. t, s 1 tear.

Comparative Example 6 A magnetic tape was produced in the same manner as in Example 1, except that in the formation of the plasma polymerized protective film layer in Example 6, the addition of oxygen gas was omitted and the gas pressure was set to 0.02 Torr.

The thickness of the plasma polymerized protective film layer at this time was 300. Comparative Example 7 In the formation of the plasma polymer m 119j M in Example 7, the addition of oxygen gas was omitted and the gas pressure was set to 0.02.
A magnetic tape was produced in the same manner as in Example 2 except that the tape was made taller. The thickness of the plasma polymerized protective film layer at this time is 2
There were 80 people.

Comparative Example 8 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 in Example 6. Magnetic tape obtained in each of Examples 6 to 10 and Comparative Examples 5 to 8 The tape was tested for durability and runnability.1. The results are shown in Table 2 below. Note that the durability and tape tension were tested under the same test conditions as those described above.

Table 2 [Results of the Invention 1 As is clear from the table above, the magnetic tapes (Examples 1 to 10) obtained by the present invention were all compared to Comparative Examples I to 8.
Compared to magnetic tapes obtained in Therefore, it can be seen that the magnetic recording medium obtained according to the present invention has further improved durability and runnability.

[Brief Description of the Drawings] Fig. 1 is a schematic sectional view showing an example of a plasma processing apparatus used in forming a plasma polymerized protective film layer, and Fig. 2 is a partially enlarged sectional view of a magnetic tape obtained by the present invention. It is a diagram. 1... Polyester film (substrate), 10...
・・Strong JM note metal false film layer (magnetic layer>, 11...
Plasma polymerized lead Zhao film layer, A...Magnetic tape (magnetic recording medium).

Claims (4)

[Claims] (1) A magnetic layer is formed on a substrate, and a plasma-polymerized protective film layer of a silicon-based organic compound containing at least silicon and oxygen is provided on the magnetic layer, and the amount of oxygen atoms relative to the amount of silicon atoms in the plasma-polymerized protective film layer is Atomic ratio 0.7-1
．． A magnetic recording medium characterized in that it is regulated within a three-fold range. (2) The magnetic layer formed on the substrate is exposed to plasma of at least a silicon-based organic compound monomer gas alone or a mixed gas of a silicon-based organic compound monomer gas and oxygen gas to perform plasma polymerization. Both forms a plasma polymerized protective inner layer of a silicon-based organic compound containing oxygen, and the atomic ratio of oxygen atoms to the silicon atomic amount in the plasma polymerized protective film layer is regulated within a range of 0.7 to 1.3 times. A method of manufacturing a magnetic recording medium, characterized in that: (3) A magnetic layer is formed on the substrate, and a plasma polymerized protective film layer of a silicon-based organic compound containing at least silicon, oxygen, and nitrogen is provided on the magnetic layer, and the oxygen content is based on the silicon atomic weight in the plasma polymerized protective film layer. The atomic weight and nitrogen atomic weight are 0.7 to 1.3 times and 0.3 to 0.
A magnetic recording medium characterized by being regulated within a seven-fold range. (4) Plasma polymerization by exposing the magnetic layer formed on the substrate to a plasma of a silicon-based organic compound monomer gas containing at least silicon and nitrogen or a mixed gas of a silicon-based organic compound monomer gas and oxygen gas. to form a plasma-polymerized protective film layer of a silicon-based organic compound containing at least oxygen and nitrogen, and the atomic ratio of the oxygen atomic weight and nitrogen atomic weight to the silicon atomic weight in the plasma-polymerized protective film layer is 0.7 to 0.7. A method for manufacturing a magnetic recording medium, characterized in that the magnetic recording medium is regulated within a range of 1.3 times and 0.3 to 0.7 times.