JPS61178722A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a protective layer capable of maintaining lubricating action for a long period and to obtain the titled magnetic recording medium having a small friction coefficient and having excellent durability and traveling property by depositing a halogen extreme-pressure agent on a ferromagnetic metallic thin film. CONSTITUTION:A ferromagnetic metallic thin film is formed on a non-magnetic carrier, and a halogen extreme-pressure agent is deposited on the ferromagnetic metallic thin film to form a recording medium. When metallic contact is locally generated in the boundary lubricating region, the halogen extreme-pressure agent to be used reacts with the metallic surface by the resulting frictional heat to form a reaction product coated film, and the friction and abrasion are prevented. Allyl bromide, etc. can be exemplified as the halogen extreme- pressure agent. In this case, the protective film is more preferably coated at the rate of 1-20mg/m<2>.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a so-called ferromagnetic metal thin film formed as a magnetic layer on a non-magnetic support by vacuum thin film forming techniques such as vacuum evaporation and sputtering. The present invention relates to a magnetic metal thin film type magnetic recording medium.

[Conventional technology]

Conventionally, as a magnetic recording medium, r
-F elog, rFezO1 containing Co
+ Fe, to, Felq containing Co, r'-F
Bertolide compound of ez03 and Fe5-,
Powder magnetic materials such as ferromagnetic powders such as ferromagnetic oxide powders such as ferromagnetic powders containing Co and Cr01, or alloy magnetic powders containing Fe, Co, Ni, etc. as main components, are combined with vinyl chloride-vinyl acetate copolymers, polyester resins, Applying magnetic paint dispersed in an organic binder such as polyurethane resin.
Coated magnetic recording media obtained by drying are widely used.

In response, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as metals such as iron, cobalt-nickel, and alloys such as Go-Ni have been developed using vacuum evaporation methods, sputtering methods, ion blating methods, etc. A magnetic recording medium with a so-called ferromagnetic metal film directly deposited on a non-magnetic support such as a polyester film or a polyimide film using vacuum thin film formation technology has been proposed and is attracting attention. This ferromagnetic gold thin film type magnetic recording medium not only has a large coercive force Hc and a large residual magnetic flux density Br, but also allows the thickness of the magnetic layer to be made extremely thin, which reduces the thickness loss during recording demagnetization and reproduction. It has many advantages in terms of magnetic properties, such as being extremely small and being able to increase the packing density of the magnetic material because it is not necessary to mix an organic binder, which is a non-magnetic material, into the magnetic layer.

However, in the above-mentioned ferromagnetic metal thin film type magnetic recording medium, the surface smoothness of the magnetic layer is extremely good, so the effective contact area is large (as a result, adhesion phenomenon (so-called sticking) easily occurs. or the coefficient of friction increases, etc.
It has many shortcomings in terms of durability, running performance, etc., and improving them is a major issue.

Therefore, for example, the surface of the magnetic layer of the magnetic recording medium, that is, the ferromagnetic metal iX film, may be coated with fatty acids, fatty acid esters, etc.
Attempts have been made to improve the durability and runnability by forming a protective film by applying an I2I lubricant or the like.

[Problem that the invention seeks to solve]

By the way, when a protective film is formed by applying a lubricant as described above, the coefficient of friction is initially reduced and running properties are improved, but the adhesion force of the lubricant to the ferromagnetic metal thin film increases. Since the lubricant is not very large, there is a problem in that the lubricant is gradually scraped off by a magnetic head or the like, resulting in a sudden drop in effectiveness.

Therefore, there is a demand for further improvement of the above lubricants.

Therefore, the present invention aims to provide a ferromagnetic metal thin film type magnetic recording medium that maintains a lubricating effect over a long period of time, has a small friction coefficient, and has excellent wear resistance and durability, and solves the above-mentioned problems. This is what we are trying to solve.

[Means for solving problems]

As a result of intensive research to achieve the above-mentioned purpose, the present inventors discovered that extreme pressure agents containing halogen elements such as chlorine, bromine, and iodine in their molecules are effective in sustaining the lubricating effect. The present invention has been completed, and is characterized in that a ferromagnetic metal thin film is formed on a non-magnetic support, and a halogen-based extreme pressure agent is adhered to the ferromagnetic metal thin film. .

The halogen-based extreme pressure agent used in the present invention has a boundary i
When metal contact occurs partially in the sliding area, the resulting frictional heat reacts with the metal surface, resulting in a reaction product coating (generally thought to be a metal halide coating, but the details are unknown). ) to prevent friction and wear.

The halogen-based extreme pressure agent is allyl bromide.

Bromine compounds such as octadecyl bromide, cyclohexyl bromide, stearyl bromide, hensyl bromide, iodine compounds such as hensyl iodide, allyl iodide, butyl iodide, octadecyl iodide, cyclohexyl iodide, hexachloroethane, monochlorobenzene, Examples include chlorine compounds such as chlorinated paraffin, chlorinated diphenyl, chlorinated oil and fat, methyl trichlorostearate, pentachloropentadienoic acid, and ester or imide derivatives of hexachloronaphthenic acid compounds.

As a method for attaching these halogen-based extreme pressure agents to a ferromagnetic metal thin film, the above-mentioned halogen-based extreme pressure agents are dissolved alone in an R medium such as acetone, ethyl ether, freon, toluene, isooctane, hexane, etc. /8 solution can be applied or sprayed onto the surface of the ferromagnetic metal thin film, or conversely, the ferromagnetic metal thin film can be immersed in this solution and dried, but it is usually added to a lubricant that acts as an oil-based agent. A method is adopted in which a protective layer is formed by depositing a protective layer on a ferromagnetic metal thin film.

Here, the coating amount of the protective film is 0.5 to 10Qmg.
/n? It is preferable that the amount is 1 to 20 mg/m, and more preferably 1 to 20 mg/m. If the amount applied is too small, the effects of lowering the friction coefficient and improving wear resistance and durability will not be achieved, while on the other hand, it is too large. Then, a sticking phenomenon occurs between the sliding member and the ferromagnetic metal thin film, and the running performance becomes worse. The amount of the halogen-based extreme pressure agent mixed into the lubricant is preferably in the range of 0.1 to 30% by weight, but the amount added varies depending on the type of lubricant.

Further, as the lubricant used in combination with the above-mentioned halogen-based extreme pressure agent, fatty acids, fatty acid esters, fatty acid amides, aliphatic alcohols, paraffins, silicones, fluorine-based surfactants, etc. can be used.

Fatty acids include lauric acid and myristic acid.

palmitic acid, stearic acid, behenic acid, oleic acid,
Those having 12 or more carbon atoms such as linoleic acid and linoleic acid can be used.

Ethyl stearate is a fatty acid ester.

Butyl stearate, amyl stearate, stearic acid monoglyceride, oleic acid monoglyceride, etc. can be used.

Examples of fatty acid amides include caproic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide.

Oleic acid amide, linoleic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, etc. can be used.

Cetyl alcohol is an aliphatic alcohol.

Stearyl alcohol etc. can be used.

As the paraffin, saturated hydrocarbons such as n-nonadecane, n-tridecane, and n-tocone can be used.

As silicones, polysiloxanes in which hydrogen is partially substituted with alkyl groups or phenyl groups, and those modified with fatty acids, aliphatic alcohols, fatty acid amides, etc. can be used.

As the fluorine-based surfactant, pertetetrafurkylcarboxylic acid and perfluoroalkylsulfonic acid and Na,
Mg, Zn, A6. Fe, Co.

Salts with Ni etc., perfluoroalkyl phosphate esters, perfluoroalkyl betaines, perfluoroalkyltrimethylammonium salts, perfluoroethylene oxide,
Perfluoroalkyl aliphatic esters and the like can be used.

On the other hand, the magnetic recording medium to which the present invention is applied is one in which a ferromagnetic metal thin film is provided as a magnetic layer on a non-magnetic support, and the material of the non-magnetic support is polyester such as polyethylene terephthalate. polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, plastics such as polycarbonate, polyimide, and polyamideimide, and aluminum. Examples include alloys, light metals such as titanium alloys, and ceramics such as alumina glass. The nonmagnetic support may be in any form such as a film, sheet disk, card, or drum.

Further, as the metal material constituting the ferromagnetic metal thin film, metals such as Fe, Co, and Ni, or co-Ni alloy,
Fe-Go gold alloy Fe-Ni alloy.

Fe-Co-Ni alloy, Fe-Co-B alloy, co-N
i-Fe-B alloy or these (r.

Examples include those containing metals such as A2.

As a means for depositing these metal materials to form a ferromagnetic metal thin film, a vacuum thin film forming technique such as a vacuum evaporation method, an ion blasting method, or a sputtering method is employed.

In the vacuum evaporation method, the ferromagnetic metal material is subjected to resistance heating and high-frequency heating under a vacuum of 10 to 10 Torr.

This method involves depositing evaporated metal (ferromagnetic metal material) on a non-magnetic support by evaporating it using electron beam heating, etc.
It is broadly divided into oblique evaporation method and vertical evaporation method. The above-mentioned oblique deposition method is a method in which the above-mentioned ferromagnetic metal material is obliquely vapor-deposited on a non-magnetic support in order to obtain a high coercive force, and the above-mentioned vapor deposition is performed in an oxygen atmosphere in order to obtain a higher coercive force. Also includes things. In the above-mentioned vertical vapor deposition method, Bi, Sb, Pb, Sn, Ga, In, Cd,
A base metal bottom layer of Ge, Si, Tit, etc. is formed in advance, and the above-mentioned ferromagnetic metal material is vertically deposited on this base metal layer.

The ion blating method mentioned above is also a type of vacuum evaporation,
DC glow discharge and RF glow discharge are caused in an inert gas atmosphere of 10 to 1 O Torr, and the above-mentioned ferromagnetic metal material is evaporated during the discharge.

The sputtering method described above involves causing a glow discharge in an atmosphere mainly composed of argon gas at 10 to 10 Torr, and using the generated argon gas ions to knock out atoms on the target surface. , two-pole, three-pole sputtering method, high-frequency sputtering method, and magnetron sputtering method using magnetron discharge.

[Effect]

As mentioned above, by attaching a halogen-based extreme pressure agent to the surface of the ferromagnetic metal thin film, which is the magnetic layer of the ferromagnetic metal thin film type magnetic recording medium, it has good adhesion to the ferromagnetic metal thin film and prevents friction and wear. A highly effective protective layer is formed.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Example 1: Cobalt) C was deposited on a 12 μm thick polyethylene terephthalate film using a vacuum evaporation device.

was obliquely deposited at an incident angle of 50° to 90”, and the film thickness was approximately 1300.
A ferromagnetic metal thin film was formed.

Next, on the ferromagnetic metal thin film, a solution of stearic acid mixed with 10% by weight of allyl bromide diluted to 1% by weight/vo with a solvent (acetone:ethyl ether = 1:1) was applied (coating amount: 20+ng/n). ?) I. I created a sample tape.

Example 2 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of cyclohexyl bromide was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 3 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of benzyl bromide was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 4 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 1% by weight of benzyl iodide was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 5 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of benzyl iodide was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 6 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 20% by weight of benzyl iodide was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 7 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of hexachloroethane was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 8 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of chlorinated paraffin was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 9 A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of methyl trichlorostearate was used instead of stearic acid mixed with 10% by weight of allyl bromide.

Example 10゜A sample tape was prepared in the same manner as in Example 1, except that stearic acid mixed with 10% by weight of pentachloropentadiene acid was used instead of stearic acid mixed with 10% by weight of allyl bromide. .

Comparative Example A sample tape was prepared in the same manner as in Example 1, except that simple stearic acid was used instead of stearic acid mixed with 10% by weight of allyl bromide.

The relationship between the number of runs and the decrease in output was investigated for each sample tape obtained in the above Examples and Comparative Examples, and the results are shown in the sixth table.

(Margins below) From the table above, it was found that the magnetic recording media of each example according to the present invention had little decrease in output even when the number of runs increased, and still durability and shuttle durability were improved. Ta.

Further, in each of the above Examples, almost no adhesive wear occurred.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Since a halogen-based extreme pressure agent is attached to the ferromagnetic metal thin film, a protective layer is formed that maintains its lubricating effect over a long period of time.
It is possible to obtain a ferromagnetic metal thin film type magnetic recording medium that has a small coefficient of friction and excellent durability and runnability.

Claims (1)

[Claims] 1. A magnetic recording medium comprising: a ferromagnetic metal thin film formed on a non-magnetic support; and a halogen extreme pressure agent adhered to the ferromagnetic metal thin film.