JPH026133B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to magnetic recording media, particularly to vapor-deposited magnetic recording media. Evaporated recording media are manufactured by methods such as vacuum evaporation, sputtering, and ion plating, in which ferromagnetic metal is evaporated and physically deposited onto a substrate in a vacuum or in a specific gas atmosphere. Ru. These magnetic recording media can significantly reduce the thickness of the ferromagnetic metal layer compared to conventional coated magnetic recording media. Therefore, vapor deposition recording media are promising recording media for applications that require high-density recording, such as video signals and digitized audio signals. However, in order for vapor-deposited magnetic recording media to perform high-density recording as described above, it is necessary to have stable running properties and properties that are not easily damaged by wear. is susceptible to wear and damage; for example, when used as a VTR tape, the surface is damaged after just a few runs, leading to a decrease in output and problems with durability and runnability. In order to improve these problems, there is a method of providing a plating film of rhodium, nickel, chromium, etc. on the deposited layer, and in the case of a deposited layer made of cobalt alloy, the surface is oxidized at an appropriate temperature and humidity. Methods (e.g. Japanese Patent Publication No. 42-20025, USP3353166)
No.) A method in which an alloy magnetic thin film is brought into contact with sulfuric acid, then heat-treated to form an oxide film on the surface, and then a lubricant is impregnated into the film (for example, BP1265175).As a protective film, SiO, SiO ₂ , Vapor deposition of precious metals, metal oxides, carbides, nitrides, sulfides, fluorides, etc.
A method of forming by sputtering, ion plating (for example, USP No. 3109746, No. 3353166,
JP-A No. 50-80102, No. 50-93404, No. 51-
No. 112307, No. 50-93604, No. 51-58304, No. 50
−104602, No. 50-123408, No. 50-146303,
No. 51-56202, No. 53-21901, No. 53-21902,
No. 53-30304) is known. Magnetic recording media in which an inorganic protective layer is provided on these deposited layers are not yet suitable for practical use. Furthermore, a method of forming a resin film on the protective layer (JP-A No. 54-123922, No. 54-123923, No. 56-
No. 71284, No. 56-71285, No. 56-71286, No. 56
-71287) is also known, but in this case,
Although it is necessary to make the resin coating thin, it is difficult to make the resin coating thin, which results in head spacing loss, making it unsuitable for high-density recording media. An object of the present invention is to provide a magnetic recording medium that has excellent running stability and durability. The object of the present invention is to provide a magnetic recording medium formed by depositing a ferromagnetic metal layer on a substrate, characterized in that a layer made of boric acid ester is provided on the surface of the ferromagnetic metal layer. It was finally achieved. The boric acid ester of the present invention is easily soluble in polar solvents such as acetone, diethyl ether, dioxane, butyl cellosolve, ethanol, aniline, toluene, etc., and is dissolved in these solvents, and the resulting solution is applied onto the vapor deposition layer. It is applied by so-called overcoating to form a layer of boric acid ester. In this case, the solvent used is preferably a relatively polar solvent such as toluene. The concentration of the boric acid ester in these solutions may be within a range in which the boric acid ester is dissolved in the solvent, but is preferably 0.05 to 0.5%. Although additives such as a binder may be added to the solution in addition to the boric ester, a solution containing only the boric ester is preferable. The boric acid ester layer may have any thickness, but from the viewpoint of reducing the resistance caused by the spacing cloth, the thickness should be 0.002~
0.2 μm, especially 0.005 to 0.01 μm is preferred. Although any compound can be used as the boric acid ester of the present invention, a compound represented by the following general formula [] is preferably used. In the above formula, R ₁ and R ₂ represent a saturated or unsaturated alkyl group or an aryl group. Representative examples of the saturated and unsaturated alkyl groups include alkyl groups and alkenyl groups. Each of the above groups includes those having a substituent, and the substituent is preferably a hydrocarbon group such as an alkyl group, an alkenyl group, or an aryl group. It is advantageous for the saturated or unsaturated alkyl group of the present invention to have a long carbon chain, and preferably has 10 to 30 carbon atoms. Since the boric acid ester of the present invention has a polar group, it has good affinity with metal surfaces, and unlike conventional resin coatings, it can be used as a protective layer on metal surfaces even when no coating is formed. Since it is strongly bonded, it is possible to reduce the thickness of the protective layer, which is also advantageous in terms of head spacing loss. Typical specific examples of the boric acid ester of the present invention are listed below. 1 Glycerol borate laurate 2 Glycerol borate balmitate 3 Glycerol borate stearate 4 Glycerol borate oleate 5 Glycerol borate isooctadecanoate 6 Glycerol borate hydroxystearate 7 Polyoxyethylene glycerol borate laurate 8 Polyoxyethylene glycerol borate palmi Tate 9 Polyoxyethylene glycerol borate stearate 10 Polyoxyethylene glycerol borate oleate 11 Polyoxyethylene glycerol isooctadecanoate 12 Glycerol borate benzoate These compounds are already known, and some of them are generally commercially available. and others can be easily synthesized by known methods. The boric acid ester according to the present invention may be used alone or in combination of two or more, and may also be used in combination with other silane coupling agents, titanate coupling agents, phosphate esters, etc. May be used in combination with other agents. Further, resins such as silicone-modified urethane, fluorinated urethane, polyester, polyvinyl chloride, polyamide, and epoxy, silicone oil, fatty acid ester, fatty acid, polyfluoroethylene, etc. may also be used in combination. To form the ferromagnetic metal layer according to the present invention,
Metals such as iron, cobalt, and nickel, Fe-Co-,
Fe−Ni, Co−Ni, Fe−Co−Ni, Fe−Rh, Fe
−Cu, Co−Au, Co−Cu, Co−Cr, Co−Cr−
Rh, Co−RE (RE; Rare, earth), Fe−RE, Fe
-A ferromagnetic alloy such as Cr-Co formed into a thin film on a substrate by vacuum deposition is used. The thickness of the magnetic film is generally 0.02 μm because it needs to be thick enough to provide sufficient output as a magnetic recording medium and thick enough to perform high-density recording.
~5.0 μm, preferably 0.05 μm to 2 μm. Substrates used include polyester, polyimide,
Plastic bases such as polyamide, polymethyl methacrylate, polycarbonate, polyether sulfone, polyethylene naphthalate, or metals or inorganic compounds such as aluminium, aluminum alloys, titanium, titanium alloys, copper, copper alloys, or glass, quartz. used. The thickness of this substrate is arbitrary, and various thicknesses are used depending on the purpose. Methods for depositing ferromagnetic metal onto a substrate are already known, and the magnetic recording medium of the present invention can be deposited by any of these known methods. These vapor deposition methods include, for example, a vacuum vapor deposition method, a sputtering method,
This is an ion plating method. Typical specific examples of the present invention are shown below. Example 1 After producing a tape on which a Co-Ni alloy was vapor-deposited (hereinafter referred to as vapor-deposited tape), a 0.1% toluene solution of glycerol borate oleate was prepared, coated on the magnetic layer with a reverse roll coater, and then cut and printed on a VTR. A tape (referred to as tape-1) was prepared. Example 2 After producing the vapor deposition tape, a 0.1% ethanol solution of glycerol borate stearate was prepared,
After coating on the magnetic layer with a reverse roll coater, it is cut into VTR tape (referred to as Tape-2).
was created. Example 3 After producing a vapor-deposited tape, a 0.1% ethanol solution of polyoxyethylene glycerol borate stearate was prepared, coated on the magnetic layer using a reverse roll coater, and then cut to obtain a VTR tape (referred to as Tape-3). Created. Comparative Example 1 After producing the vapor-deposited tape, immediately cut it.
A VTR tape (referred to as Comparative Tape-1) was produced. Comparative Example 2 After producing a vapor-deposited tape, a 0.1% toluene solution of dimethylpolysiloxane was prepared, and then a VTR tape (referred to as Comparative Tape-2) was produced. Comparative Example 3 After making a vapor deposition tape, 0.5% of oleic acid
A toluene solution was applied onto the magnetic layer using a reverse roll coater and then cut to produce a VTR tape (referred to as Comparative Tape-3). Hang each sample tape above on a VTR deck,
Table 1 shows the results of checking the TV screen for screen disturbances due to poor running.

[Table] Table 1 shows the percentage of time when the screen is disturbed due to poor running. Disturbed time/Total running time x 100 (%)
It was expressed as As is clear from the results in Table 1, the tape of the present invention provided with a layer made of boric acid ester clearly exhibits good running properties. Example 4 A vapor-deposited tape was produced, overcoated with a 0.5% toluene solution of glycerol borate oleate, cut, and made into an audio tape (tape).
4) was produced. Comparative Example 4 A vapor deposition tape was made and 0.5% of silicone oil was applied.
% toluene solution, overcoat it, cut it, and use it as an audio tape (comparison tape).
4) was produced. Comparative Example 5 A vapor-deposited tape was produced, overcoated with a 0.5% toluene solution of behenic acid, and then cut to produce an audio tape (referred to as Comparative Tape-5). Using Tape-4 and Comparative Tapes-4 and 5, the decrease in the 12.5 KHz signal and the level fluctuation of the same signal after running 1000 times were measured, and the results shown in Table 2 were obtained.

[Table] In Table 2, the smaller the variation in these values, the better the results, but the tape of the present invention clearly decreased compared to the comparative tape after repeated running.
It can be seen that the decrease in output and increase in level fluctuation indicates improved durability. Example 5 A toluene solution containing 0.1% glycerol borate oleate and 0.1% silicone oil was prepared,
The solution was applied onto the magnetic layer of the vapor-deposited tape and then cut to produce a VTR tape (Tape-5). Example 6 0.1% glycerol borate oleate,
TTS (titanate coupling agent, manufactured by Ajinomoto Co., Ltd.)
After preparing a toluene solution containing 0.1% of
A tape for VTR (tape-6) was produced. Example 7 A toluene solution containing 0.1% glycerol borate laurate and 0.05% silicone-modified urethane resin was prepared, and the solution was applied onto the magnetic layer of a vapor-deposited tape, cut, and made into a VTR tape (tape). 7) was produced. Comparative Example 6 A vapor-deposited tape was made and 0.2% of TTS was applied on the magnetic layer.
After applying the solution, it was cut to produce a VTR tape (Comparative Tape-6). Comparative Example 7 After producing a vapor deposition tape and applying a 0.1% toluene solution of silicone modified urethane resin on the magnetic layer,
It was cut to produce a VTR tape (comparison tape-7). Examples 5, 6 and 7, comparative tapes 6 and 7
The image was placed on a VTR deck, and image disturbances due to tracking deviations caused by poor running performance were observed in the same manner as above while looking at a television screen, and the results shown in Table 3 were obtained.

【table】

Claims (1)

[Scope of Claims] 1. A magnetic recording medium comprising a ferromagnetic metal layer deposited on a substrate, characterized in that a layer made of boric acid ester is provided on the surface of the ferromagnetic metal layer. 2. The magnetic recording medium according to claim 1, wherein the boric acid ester is a compound represented by the following general formula []. General formula [] [The above R ₁ and R ₂ represent a saturated or unsaturated alkyl group or aryl group. ]