JPH0343689B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a wear-resistant magnetic recording medium. Conventionally, in order to impart wear resistance to the magnetic thin film of a magnetic recording medium, a lubricant was added on the magnetic thin film.
Fluorine-based lubricants such as fluoroalkylcarboxylic acids, their metal salts, esters, and amides have been dissolved in solvents, and coatings have been formed by coating, dipping, etc.; however, the coatings are relatively easy to peel off. It had disadvantages such as being easy to use. In order to improve this drawback, the applicant previously proposed in Japanese Patent Application Laid-Open No. 59-213031 a wear-resistant film in which an alkali metal salt or alkaline earth metal salt of fluoroalkylcarboxylic acid was evaporated and formed on a magnetic thin film. proposed a magnetic recording medium. However, in order to evaporate such metal salts of fluoroalkyl carboxylic acids, the temperature is generally 150°C to 350°C.
As a result of subsequent studies, it was found that thermal decomposition occurs, and the deposited film often contains decomposition products that do not contribute as lubricants. I've come to understand. The present invention enables the formation of a vapor-deposited film of a metal salt of fluoroalkylcarboxylic acid on a magnetic thin film, which is free from decomposition products such as those described above, and has further improved wear resistance. This provides a method for producing a magnetic thin film in which an alkali metal or alkaline earth metal oxide or hydroxide and a fluoroalkyl carboxylic acid are separately evaporated, and these vapors are pre-formed on a non-magnetic substrate. A contact reaction is carried out on the magnetic thin film, and a vapor-deposited thin film of the reaction product, a metal salt of fluoroalkylcarboxylic acid, is formed on the magnetic thin film. In the above-mentioned manufacturing method of the present invention, it is of course possible to form a protective film using SiO ₂ , CaO, an organic polymer, etc. in advance on the magnetic thin film, and to pass the magnetic film through this film. Further, the above-mentioned catalytic reaction may be accelerated by heating, if necessary, during or after the vapor deposition process. Then, a vapor-deposited film of an alkali metal or alkaline earth metal and a vapor-deposited film of a fluoroalkylcarboxylic acid are deposited and laminated on the magnetic thin film, and in this state they react with each other to generate a metal salt of the fluoroalkylcarboxylic acid. The former film has a thickness in the range of 2 to 20 Å, and the latter film has a thickness in the range of 50 to 500 Å, for a total of 50 to 500 Å.
Good results can be obtained in reaction production by the thinness of the film, which is about .ANG. Next, an embodiment of the manufacturing method of the present invention will be described based on the accompanying drawings. The drawings show one example of an apparatus for carrying out the invention, 1
is a vacuum processing chamber connected to a vacuum device via an exhaust port 2; 3 and 4 indicate rollers that can rotate in any direction; for example, one of the rollers 3 is an unwinding roller 3 around which a tape-shaped magnetic recording material 5 is wound, and the other roller 4 is a winding roller. Use as 4. The magnetic recording body 5 has a thickness of 12 μm.
Non-magnetic base material made of thick polyester film
It consists of a 1500 Å thick Co-20Ni-O magnetic film,
This is prepared by a conventional method, and is prepared in a roll shape around a roller 3, and then wrapped around the other roller 4 through the circumferential surface of a metal cylindrical can 6 provided between the rollers 3 and 4, and stretched. Prepare. The can 6 is heated to 150°C by being supplied with a heating medium as necessary.
It is designed to be heated to an appropriate temperature. A partition plate 7 is vertically provided at the bottom end of the can 6, and a first evaporation source 8 consisting of a crucible or the like containing an alkali metal or alkaline earth metal hydroxide or oxide a is provided on one side of the partition plate 7. This is heated and evaporated using a resistance heating method or an electron beam heating method (not shown). In the case of hydroxide, a resistance heating method is generally used, and in the case of an oxide, an electron beam heating method is used to evaporate. Further, on the other side of the partition plate 7, fluoroalkylcarboxylic acid b
A second evaporation source 9 is provided, such as a crucible containing . In the illustrated example, the material is heated and evaporated by radiant heat from a Ta-ray heater. 10 is
The attachment prevention plates arranged on both sides of the lower end of the rotating can 6 are shown. The partition plate 7 may be either a fixed type or a movable type that can move up and down. Thus, when the partition plate 7 is provided with its upper end substantially close to the surface of the magnetic tape 5 moving on the can 6 as shown in the figure, the vapor from the first and second evaporation sources 8 and 9 on both sides of the partition plate 7 is One of the deposited films is first formed on the magnetic film, and then the other deposited film is formed on the magnetic film, without mixing with each other, in the direction of movement of the magnetic tape 5. A mutual reaction occurs between the laminated films, and when the partition plate 7 is moved downward and the partition is released, the vapor from the evaporation sources 8 and 9 on both sides is evaporated onto the tape 5. Both reactions will take place. In this case, to promote the reaction between the two, the can 6 is heated, and the heat is transmitted to both laminated layers via the tape 5, thereby promoting the reaction. As another heating means, the vapor-deposited magnetic tape can be removed from the take-up roller 3 or 4 and heated with a heater such as an oven in a separate vacuum chamber or in the atmosphere to promote the reaction. Using the above apparatus, carry out as follows. That is, the magnetic tape 5 is unwound from the roller 3 and moved at a constant speed through the circumferential surface of the rotary can 6 so as to be wound around the roller 4, and in the middle of the movement, the downward direction is The vapor a from the evaporation source 8 is evaporated onto the magnetic film surface of the evaporation source 8 to form the first evaporation layer, and then when it moves to the right side of the partition plate 7, the vapor a is evaporated from the evaporation source 9 according to the type of the fluoroalkyl carboxylic acid. Approximately 60~
The vapor b is deposited on the upper surface of the first vapor deposited layer by heating to 150° C. to polymerize and form the second vapor deposited layer. When this happens, a reaction occurs between these two layers,
A thin film of the metal salt of fluoroalkylcarboxylic acid, which is the reaction product, coats and binds the magnetic film and is wound around the roller 4 to complete the production.
During this time, it is preferable to heat the can 6 to raise the temperature of the magnetic film of the magnetic tape 5 to an appropriate temperature, especially in the case of a vapor-deposited layer of an oxide of an alkaline earth metal, which reacts relatively slowly. . In the case of heating, no thermal decomposition of the reaction products occurs. Preferably 150℃
It is preferable to maintain the temperature at a temperature not exceeding . or,
Similar good results can be obtained even if the vapor deposition layers of both types of vapors a and b are opposite to those described above. In this case, of course,
The feeding direction of the magnetic tape is reversed from the above. still,
Although not shown, the means for laminating two types of vapor deposition layers can be to provide separate vacuum evaporation processing chambers and perform the vapor deposition sequentially, or to first perform one type of vapor deposition in the same chamber and then apply the vapor deposition tape. It is optional, such as moving in the opposite direction to perform the next vapor deposition of another type. Using the above apparatus and method, various samples No. 1 to No. 9 were obtained as shown in the table below. For comparison,
Samples No. 10 and No. 11 were prepared as reference examples when metal salts of fluoroalkyl carboxylic acids were used as raw materials for direct evaporation. In this case, only the second evaporation source 9 was used. Regarding the abrasion resistance of these samples, the practically important still playback life when used as a videotape was measured. The results are shown in the table below.

[Table] As is clear from the above table, the magnetic recording material having a metal salt of fluoroalkylcarboxylic acid according to the present invention is manufactured by first evaporating the proposed metal salt of fluoroalkylcarboxylic acid and depositing the same. A product with significantly improved still playback life compared to a recording medium can be obtained. The thickness of the reaction product film according to the present invention is preferably 300 Å or less. As described above, according to the present invention, an oxide or hydroxide of an alkali metal or an alkaline earth metal and a fluoroalkylcarboxylic acid are evaporated, and the reaction product fluorine is deposited on the magnetic film through a reaction between the two. Since a metal salt of an alkylcarboxylic acid is formed, it has the effect of significantly improving wear resistance compared to a method in which a metal salt of a fluoroalkylcarboxylic acid is directly evaporated and deposited. .

[Brief explanation of drawings]

The drawing shows a cross-sectional view of an example of an apparatus for carrying out the invention. 1... Vacuum processing chamber, 3, 4... Roller, 5...
...magnetic recording medium, 6...can, 7...partition plate, 8
...First evaporation source, 9... Second evaporation source, a... Oxide or hydroxide of an alkali metal or alkaline earth metal, b... Fluoroalkylcarboxylic acid.

Claims (1)

[Claims] 1. The oxide or hydroxide of an alkali metal or alkaline earth metal and the fluoroalkyl carboxylic acid are evaporated separately, and these vapors are brought into contact reaction on a magnetic thin film previously formed on a non-magnetic substrate, and the magnetic thin film is A method for producing a wear-resistant magnetic recording material, characterized in that a thin film of a metal salt of fluoroalkylcarboxylic acid, which is a reaction product thereof, is formed thereon.