JPS6361417A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To decrease coefft. of friction and to improve runnability and durability by forming a plasma polymn. layer into which fine metallic particles are incorporated to form ruggedness on the surface on a substrate and providing a magnetic layer thereon. CONSTITUTION:The plasma polymn. layer 14 into which the metallic particles are incorporated to form ruggedness on the surface is formed on the substrate 1 consisting of a polyester film, etc., and the magnetic layer 15 is provided thereon to form a magnetic tape A. Metal is evaporated at the time of plasma polymn. to incorporate the fine metallic particles into said layer. Zn Al, Ni, Co, Cr, Ti, Fe, etc., or the alloys thereof are used as said metal. Gaseous monomers of a hydrocarbon, fluorine org. compd., silicon org. compd., org. metal compd., etc., are used as the monomer of the org. compd. to be used in the plasma polymn. The compounding ratio of the fine metallic particles in the polymerized film is preferably 10-70wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium and a method of manufacturing the same, and more particularly to a magnetic recording medium with a small coefficient of friction and excellent durability and a method of manufacturing the same.

[Conventional technology].

Generally, metals or their alloys are deposited on a base film by vacuum evaporation, sputtering, etc.
Alternatively, magnetic recording media made by bonding magnetic powder together with a binder component onto a base film are susceptible to abrasion of the magnetic layer due to violent sliding contact with a magnetic head etc. during recording and reproduction. Although the magnetic metal thin film layer has characteristics suitable for high-density recording, it has a large coefficient of friction with the magnetic head and is easily subject to wear and damage.

For this reason, durability has been conventionally improved by providing various protective PI layers on the magnetic layer. Publication No. 53-88704, Japanese Patent Publication No. 58-94
130), or by forming a thin film of a polymer compound by plasma polymerization of a monomer gas of an organic compound (JP-A-58-88828, JP-A-58-60427),
It has also been proposed to form a carbon-hydrogen-based hydrogen odor by ionization plasma decomposition polymerization (Japanese Unexamined Patent Publication No. 157726/1983).

[Problem that the invention seeks to solve]

However, these protective film layers provided on the magnetic layer do not yet have sufficient durability, and are likely to wear out in a relatively short period of time due to sliding contact with the magnetic head, and have not yet achieved sufficient durability. It has not been done.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation, and consists of forming a plasma polymerized film layer containing fine metal particles and forming an uneven surface on a substrate, and forming a magnetic layer on this plasma polymerized film layer. By forming a plasma polymerized film layer with an uneven surface, unevenness is formed on the surface of the magnetic layer, reducing the actual contact area when sliding with a magnetic head, etc., and increasing the coefficient of friction. It has been made smaller and its durability has been sufficiently improved. Further, by further forming a lubricant layer on the magnetic layer, the durability is further improved.

In this invention, the plasma polymerized film layer formed on the substrate is formed by exposing the substrate to a plasma of monomer gas of an organic compound in a summer air atmosphere to perform plasma polymerization, and at the same time, a vapor stream obtained by heating and evaporating the metal. When the metal is heated and evaporated at the same time as the plasma polymerization of the organic compound, the heated and evaporated metal becomes fine particles and adheres to the substrate, forming fine metal particles. A plasma-polymerized film layer of an organic compound containing the organic compound and having an uneven surface is formed. Due to the unevenness of this plasma polymerized film layer, when a magnetic layer is formed thereon, this plasma polymerized I! ! Since irregularities are formed on the surface of the magnetic layer along the irregularities of the II layer, the actual contact area when sliding with a magnetic head etc. is reduced, the coefficient of friction is sufficiently reduced, and running properties are improved. Durability is sufficiently improved.

As described above, metals such as zinc, aluminum, nickel, cobalt, chromium, titanium, and iron, or alloys thereof, are preferably used as metals that are heated and evaporated in a metal evaporation source at the same time as plasma polymerization. These metals are heated and evaporated by resistance heating or electron gun heating, directed toward the substrate, and deposited on the substrate in the form of fine particles.

In addition, monomer gases for organic compounds used in plasma polymerization include, for example, monomer gases for hydrocarbon compounds such as methane, propane, ethylene, and propylene;
Monomer gas of fluorine-based organic compounds such as c2F4, c3F6, C3F, monomer gas of silicon-based organic compounds such as tetramethylsilane, hexamethyldisilane, hexamethyldisilazane, hexamethylsiloxane, octamethylcyclotetrasiloxane, tetramethyl tin,
Monomer gases of organometallic compounds such as tetramethylgermanium, ferrocene, pentaethoxytantalum, and titanium tetraisopropoxide are preferably used. The monomer gas of these organic compounds can be used alone or mixed with rare gas, hydrogen gas, oxygen gas, etc.
Plasma polymerization occurs on the substrate by MHz high frequency or 2.56 GHz microwave, and at the same time a metal vapor flow is directed, resulting in plasma polymerization that contains fine metal particles and forms irregularities on the surface. A membrane layer is formed on the substrate.

The proportion of metal fine particles in the plasma polymerized film layer formed in this way is preferably within the range of 10 to 70% by weight based on the total components of the plasma polymerized film layer,
If the amount is too small or too large, unevenness cannot be formed satisfactorily on the surface. In addition, the unevenness on the surface of the plasma polymerized film layer is
The width within the range of 0.01 to 0.20 μm is 1×10
It is preferable that 12 to 1×10 14 pieces/cd are formed. If the width is too narrow or too small, the desired effect cannot be obtained, and if the width is too wide or too large, it will adversely affect the electromagnetic conversion characteristics. The width and number of these irregularities are controlled by controlling the gas pressure, high frequency power, microwave power, etc. when simultaneously performing metal heating evaporation and plasma polymerization. When polymerization is performed simultaneously, the gas pressure, high frequency power, and microwave power form good irregularities on the surface of the plasma polymerized protective film layer, and also improve the adhesion between the plasma polymerized film layer containing fine metal particles and the magnetic layer. In order to improve
It is preferably within the range of 2W/cd, and the gas pressure is 0.
03 to 1.5 torr, and the high frequency power is 0.05
~1W/cn! , the microwave power is 0.05~I W
/an! It is more preferable to set it within the range of . In addition, the thickness of the plasma polymerized film layer formed in this manner with an uneven surface is preferably within the range of 50 to 1000 layers, and if the film thickness is too thin, the plasma polymerized film layer with sufficient unevenness No layer is obtained, and runnability and durability are not sufficiently improved. Moreover, if it is too thick, cracks may occur due to internal stress, which is not preferable.

The magnetic layer formed on the plasma polymerized film layer thus formed consists of γ-Fe203 powder, Fe3O4 powder,
Magnetic powders such as Co-containing r-Fe203 powder, CO-containing Fe3O4 powder, Fe powder, CO powder, and Fe-Ni powder are combined with the binder component and R? Co, Fe, Ni, Co-N, Co, Fe, Ni, Co-N, etc.
i alloy, Co-Cr alloy, Co-P alloy, Co-N1-
It is formed by depositing a ferromagnetic material such as P alloy on a substrate by means such as vacuum evaporation, ion blasting, sputtering, or plating.

When the magnetic layer thus formed is further laminated with a lubricant layer, the friction coefficient is further reduced and the durability is further improved. The lubricant layer laminated on the magnetic layer is
A lubricant is dissolved in a suitable solvent such as methyl isobutyl ketone, methyl ethyl ketone, isopropyl alcohol, benzene, toluene, freon, cyclohexanone, ethyl acetate, tetrahydrofuran, dimethylformamide, dioxane, etc., and a magnetic material is added to the solution obtained by dissolving the lubricant. The magnetic layer is deposited by dipping the layer, or by coating or spraying the solution on the preformed magnetic layer, and then a lubricant is applied to the magnetic layer by a method such as plasma polymerization, CVD, sputtering, or vacuum deposition. It can also be deposited by a method of depositing on top.

Suitable lubricants used include aliphatic lubricants, fluorine-based lubricants, silicone-based lubricants, and hydrocarbon-based lubricants. Among the aliphatic lubricants, lauric acid , myristic acid, palmitic acid,
Fatty acids such as stearic acid and behenic acid, metal salts of fatty acids such as zinc stearate and cobalt stearate, fatty acid esters such as n-butyl stearate and octyl myristate, fatty alcohols such as stearyl alcohol and myristyl alcohol, trimethyl Examples include chlorides such as stearyl ammonium chloride and stearoyl chloride, and amines such as stearylamine, stearylamine acetate, and stearylamine hydrochloride.

As the fluorine-based lubricant, perfluoropolyether, perfluoroalkyl polyether, etc. are preferably used, and specific examples of commercially available products include Guyfroil #20 manufactured by Daikin Corporation and Talytox M1 Clytox I manufactured by DuPont. Examples of silicone lubricants include silicone oil, modified silicone oil, etc., and hydrocarbon lubricants include:
Examples include paraffin, squalane, wax, and the like. Among these lubricants, those having polar groups are more preferably used because they have good adhesion to the magnetic layer and are particularly effective in lowering the coefficient of friction.

When used, one type or a mixture of two or more of them is used, and the amount of coating is preferably within the range of forming a film of 20 to 200 layers on the magnetic layer.
If the thickness is thinner than 200 mm, the desired effect cannot be obtained, and if the thickness is thicker than 200 mm, the spacing loss will be too large, which will adversely affect the electrical characteristics.

Magnetic recording media formed in this way include magnetic tapes based on synthetic resin films such as polyester films and polyimide films, synthetic resin films,
It includes various forms of structures that come into sliding contact with a magnetic head, such as magnetic disks and magnetic drums whose bases are disks and drums made of aluminum plates, glass plates, etc.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 Using the plasma processing apparatus shown in FIG.
The polyester film l is placed in the raw roll 3 in the processing tank 2.
2 along the cylindrical can 5 via the guide roll 4.
The film was moved at a speed of m/min, and further wound onto a winding roll 7 via a guide roll 6. Next, zinc 9 is heated and evaporated with an electron gun in a metal evaporation source 8 disposed below the cylindrical can 5, and at the same time, methane monomer gas is introduced into the processing tank 2 from a gas introduction pipe 10 attached to the processing tank 2. was introduced at a flow rate of 100 seconds, the gas pressure was set to 0.07 Torr, and a high frequency of 13.56 MHz was applied to the electrode 11 at 100 W to perform plasma polymerization to form a plasma polymerized film layer. The thickness of the plasma polymerized film layer at this time was 300 mm, containing fine particles of zinc and zinc oxide, and having irregularities of 0.03 μm in width on the surface of 1.3×1013
pcs/d were formed. Next, the polyester film with the plasma-polymerized film layer formed thereon was loaded into a vacuum evaporation device, and the cobalt was heated and evaporated under a vacuum of lXl0-5 torr to form a ferromagnetic metal made of cobalt with a thickness of 1500 μm on the polyester film. A thin film layer was formed. Thereafter, the magnetic tape A is cut to a predetermined width, and a plasma polymerized film layer 14 containing uneven metal particles and a ferromagnetic metal thin film layer 15 are sequentially laminated on a polyester film 1 as shown in FIG. I made it. In addition, 12 in Figure 1
1 is an exhaust system for reducing the pressure inside the processing tank 2, and 13 is a high frequency power source for applying high frequency to the electrode 11.

Example 2 Aluminum and aluminum oxide were deposited on the substrate to a thickness of 400 mm in the same manner as in Example 1, except that aluminum was heated and evaporated instead of zinc in the formation of the plasma polymerized film layer in Example 1. Contains fine particles with a width of 0.
A magnetic tape A was prepared by forming a plasma polymerized film layer having 2.1×10 13/d of unevenness of 0.5 μm.

Example 3 A plasma-polymerized film layer was formed on the substrate in the same manner as in Example 1, except that tetramethylsilane monomer gas was introduced at a flow rate of 200 seconds instead of methane monomer gas. A magnetic tape A was produced by forming a plasma polymerized film layer having a thickness of 300 mm, containing fine particles of zinc and zinc oxide, and having 4×1013 unevenness/crA with a width of 0.02 μm.

Example 4 In Example 1, after forming the ferromagnetic metal thin film layer, 0.1% of stearic acid was further applied on the ferromagnetic metal thin film layer.
On a polyester film 1 as shown in FIG. 3 in the same manner as in Example 1 except that a 50% by weight toluene solution was applied and dried to form a 50 mm thick lubricant layer made of stearic acid, Plasma polymerized film ML4 containing metal fine particles having irregularities, ferromagnetic metal thin film layer 15, and lubricant layer 16
A magnetic tape B was prepared by sequentially laminating the following layers.

Example 5 In Example 2, after forming the ferromagnetic metal thin film layer, 0.1% of stearic acid was further applied on the ferromagnetic metal thin film layer.
A magnetic tape B as shown in FIG. 3 was prepared in the same manner as in Example 2, except that a 50% by weight toluene solution was applied and dried to form a 50 mm thick lubricant layer made of stearic acid.

Example 6 In Example 3, after forming the ferromagnetic fully refracting thin film layer, 0.1% of stearic acid was further applied on the ferromagnetic metal thin film layer.
A magnetic tape B as shown in FIG. 3 was prepared in the same manner as in Example 3, except that a 50% by weight toluene solution was applied and dried to form a lubricant layer of stearic acid with a thickness of 50 mm.

Example 7 α-Fe magnetic powder 600 parts by weight S-LEC CN (manufactured by Miki Kagaku Kogyo 80, vinyl chloride-hinyl acetate copolymer) Bandesox T-5250 (large 30, manufactured by Nippon Ink Chemical Co., Ltd., urethane elastomer) Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.,
Trifunctional low molecular weight isocyanate compound) Methyl isobutyl ketone 400〃Toluene
400 This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint, and this magnetic paint was applied onto the plasma polymerized film layer formed on the polyester film in Example 1 so that the dry thickness was 4 μm. A magnetic tape was produced in the same manner as in Example 1, except that the magnetic layer was formed by coating and drying.

Example 8 After forming the magnetic layer in Example 7, a 0.1% by weight toluene solution of stearic acid was applied on the magnetic layer and dried to form a lubricant made of stearic acid with a thickness of 50 mm. A magnetic tape was produced in the same manner as in Example 7 except that the layers were formed.

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

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 4 except that the formation of the plasma polymerized film layer was omitted.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 7 except that the formation of the plasma polymerized film layer was omitted.

Comparative Example 4 A magnetic tape was produced in the same manner as in Example 8 except that the formation of the plasma polymerized film layer was omitted.

The coefficient of friction was measured for the magnetic tapes obtained in each Example and each Comparative Example, and the durability was tested. The durability test was conducted by measuring the still life using a still testing machine.

Table 1 below shows the results.

Table 1 [Effects of the Invention] As is clear from the above table, the magnetic tapes obtained according to the present invention (Examples 1 to 8) are the same as Comparative Examples 1 to 4.
Compared to the magnetic tape obtained by the present invention, the coefficient of friction is smaller and the still life is longer, which indicates that the magnetic recording medium obtained by the present invention is significantly more durable.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing one example of a plasma processing apparatus, and FIGS. 2 and 3 are partially enlarged sectional views of a magnetic tape obtained according to the present invention. DESCRIPTION OF SYMBOLS 1... Polyester film (substrate), 14... Plasma polymerized film layer, 15... Ferromagnetic metal thin film layer (magnetic layer), 16... Lubricant layer, A, B... Magnetic tape ( (Magnetic recording media) Patent applicant Hitachi Maxell Ltd. Figure 1

Claims (1)

[Claims] 1. Magnetic recording characterized in that a plasma polymerized film layer containing fine metal particles and having an uneven surface is formed on a substrate, and a magnetic layer is provided on the plasma polymerized film layer. Medium 2: A plasma polymerized film layer containing fine metal particles and having an uneven surface was formed on the substrate, a magnetic layer was provided on the plasma polymerized film layer, and a lubricant layer was further provided on the magnetic layer. A magnetic recording medium 3 characterized in that a substrate is exposed to plasma of a monomer gas of an organic compound in a vacuum atmosphere to perform plasma polymerization, and at the same time, a vapor flow obtained by heating and evaporating the metal is directed toward the substrate. A method for manufacturing a magnetic recording medium 4, which comprises forming a plasma polymerized film layer containing fine metal particles to form an uneven surface on a substrate, and then forming a magnetic layer on this plasma polymerized film layer. , the substrate is exposed to a plasma of monomer gas of an organic compound in a vacuum atmosphere to perform plasma polymerization, and at the same time, a vapor flow obtained by heating and evaporating the metal is directed toward the substrate to contain fine metal particles and coat the surface. A magnetic recording medium characterized in that a plasma polymerized film layer with unevenness is formed on a substrate, a magnetic layer is then formed on this plasma polymerized film layer, and a lubricant layer is further formed on this magnetic layer. manufacturing method