JPH01208728A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent corrosion resistance by coating a rust inhibitor on a thin ferromagnetic metallic film and drying the coating, then sliding rotating bodies such as rolls on this rust inhibitor layer, thereby pressing the rust inhibitor onto the thin ferromagnetic metallic film. CONSTITUTION:At least the rust inhibitor layer 3 is provided on the surface of the thin ferromagnetic metallic film 2 of the magnetic recording medium constituted by providing the thin ferromagnetic metallic film layer 2 on a nonmagnetic substrate 1 and thereafter, the rotting bodies are brought into sliding contact with the surface of the thin ferromagnetic metallic film 2. The film thickness of the rust inhibitor layer 3 is preferably within a 20-500Angstrom range. The rust inhibitor includes, for example, a straight chain amine compd., nitrosonaphthol, etc. The magnetic recording medium formed with the rust inhibitor layer 3 is passed between two pieces of the rotating bodies such as rolls, by which the outside peripheral faces of the rotating bodies are brought into sliding contact with the surface of the thin ferromagnetic metallic film 2 and the rust inhibitor is mechanochemically adsorbed on the thin ferromagnetic metallic film 2. The rust inhibitor molecules which are heretofore merely ridden on the thin ferromagnetic metallic film 2 are chemically adsorbed to the thin ferromagnetic metallic film 2 and the corrosion inhibitive function over the entire part of the magnetic recording medium is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic recording medium. Specifically, the present invention provides improvements in corrosion resistance. The present invention relates to a method of manufacturing a magnetic recording medium.

[Prior Art] Magnetic recording media that have been widely used in the past include a magnetic medium consisting of 1 part acicular magnetic powder and 1 part polymer-binder on a non-magnetic substrate 1. Coating layer with magnetic layer formed inside!
This is a magnetic recording medium.

Currently, there is a trend toward higher density magnetic recording + IT production equipment, and there is a demand for magnetic recording media with excellent short wavelength recording characteristics.

But l? There is a limit to how short wavelength recording characteristics of 711-type magnetic recording media can be defeated. On the other hand, co, Co
C such as Ni, CoN1P, CoCr, etc.

A metal thin film type magnetic recording medium in which a ferromagnetic material having a component of 41 non-magnetic binders! Since it is not exposed to heat, it is possible to obtain a very high residual magnetic flux density, and since the magnetic layer can be formed extremely thin, it has the advantage of high output and excellent short wavelength response. Due to this feature, thin-film magnetic recording media have recently become popular among magnetic media.

Thin-film J9J magnetic recording media have a high magnetic recording density and have good short wavelength recording properties, but on the other hand, they are relatively susceptible to corrosion due to the exposed magnetic layer, and have poor corrosion resistance. It has the disadvantage of being susceptible to magnetic deterioration (I'), which is a major problem in practical use.

In order to solve this problem, for example, [
:, attempts have been made to apply a nitrogen-containing rust preventive agent (inhibitor) to the surface of a ferromagnetic metal thin film type magnetic recording medium to increase its anticorrosion function (Japanese Patent Application Laid-open No. 1983-1992).
-194138S) Publication No. 59-3724 Schiff Duke N
, 82-t 72530 s; - Public + V).

However, unlike in an aqueous solution, in these popular magnetic recording media, it is difficult to chemically adsorb a sufficient number of inhibitor molecules to exert the anticorrosion effect in 1 minute.

In particular, 1. [At the time of production, the inhibitor layer can be formed in one step, which is easy to apply, etc., and the workability is high.This method cannot eliminate the disadvantages mentioned in 1-1, and as a result, the corrosion protection can be improved by 1. It was difficult to make it effective.

[Problems to be Solved by the Invention] The present invention aims to solve the drawback of low corrosion resistance of the prior art described in 1-1 above, and thereby provide a magnetic recording medium with excellent corrosion resistance. do.

[Steps to Solve the Problems] As a result of many years of extensive experimentation and prototyping by the inventors of the present invention, a magnetic recording medium in which a ferromagnetic metal thin film layer is provided on a non-magnetic substrate 1 has been developed. It has been discovered that a magnetic recording medium with excellent corrosion resistance can be obtained by providing at least a rust preventive layer on the surface of a magnetic metal thin film and then bringing a rotating body into sliding contact with the surface of the ferromagnetic metal thin film. The present invention was completed based on this knowledge.

FIG. 1 is a schematic diagram showing the cross-sectional structure of the magnetic recording medium of the present invention.

As shown in FIG. 1, a ferromagnetic metal thin film 2 serving as a magnetic layer is provided on the magnetic substrate 1, and a rust preventive layer 3 is laminated on the ferromagnetic metal thin film 1-. has been done.

If desired, as shown in FIG.
-1, a lubricant layer 4 can be laminated on top of the lubricant layer 4.

The anticorrosion function of rust preventive agents (inhibitors) is caused by chemical adsorption of the inhibitors onto metal surfaces (or oxide surfaces). However, even if the inhibitor can be introduced into the magnetic film 1- by applying a solvent containing the inhibitor or exposing it to its vapor, not all of it will be chemisorbed. Inhibitor molecules that are just physically present have a certain degree of anticorrosion effect, but they cannot prevent corrosive gases or N20 from entering or adsorbing, and their anticorrosion ability is low.

iI: Although the exact mechanism has not yet been elucidated and is still in the realm of speculation, the present invention uses a mechanical mechanism called sliding.
(in history, probably due to friction during sliding)
Due to the effect of 17ul), chemisorption progresses mechanically/chemically, and at the end of the day, the inhibitor molecules that were only present in rll- are also chemisorbed, and the anticorrosion function is improved. Seem.

Although the thickness of the rust preventive layer itself is not an essential characteristic of the present invention,
- Preferably, there are 20 to 500 people in the membrane. If there are less than 20 people, it is not only difficult to form a layer of anti-corrosion agent with a uniform thickness, but there is also a risk that the anti-corrosion effect will be insufficient. ,
This causes a problem of spacing loss 5 between the cards, which is undesirable.

Examples of rust preventives that can be used in the magnetic recording medium of the present invention include linear amine compounds, cyclic amine compounds, amide compounds, amine 14i, and esters.

Examples of linear amine compounds include oleylamine, N
-Methyloctadecylamine, oquinethylenedodenylamine'':'l. Examples of cyclic amine compounds include benzimidazole, 2-aminobenzimidazole, 2-mercaptobenzimidazole, and 5-chlorobenzimidazole.

5-nitrobenzimidazole, benzotriacey/l
/, 5-nitrobenz'triazolebenzimidazole, benzotriazole fatty acid salt, and nitrosonaphthol τ.

Examples of the amide compound include lauric acid amide, stearic acid amide, and oleic acid amide. Examples of amine salts include octadecylamine acetate and alkylpropylene diamine acetate '9.

Examples of esters include sorbitan monopalmitate. Others: butylhydroxyanisole, dibutylhydroxytoluene, benzotriazole, benzotriazole laurylamine, hydroquinone, dimethylaminoethylene methacrylate, triphenylphosphite, tridecylphosphite, trilauryltrithiophosphite, butylphosphate, dilaurylthionopropio Phenol-based, amine-based, phosphorus-based, sulfur-based, organic acid-based, quinone-based anti-SIv agents, such as nate, nrubitol, propylene glycol, and hydroquine, are used. A rust preventive agent consisting of a nitrogen-containing compound is preferred.

As described above, in the magnetic recording medium of the present invention, a lubricant layer can be laminated on top of the rust preventive layer, if desired.

Examples of lubricants that can be used in the present invention include aliphatic lubricants,
These include fluorine-based lubricants, silicone-based lubricants, and hydrocarbon-based lubricants.

As the aliphatic lubricant, fatty acids, metal salts of fatty acids, fatty acid esters, fatty acid amides, aliphatic alcohols, etc. are used. +lU fatty acids include, for example, lauric acid, myristic acid, palmitic acid, oleic acid,
Stearic acid, behenic acid, etc. are used. In addition, examples of these metal salts include magnesium salts, aluminum salts, lithium salts, sodium salts, calcium salts,
Iron salts, cobalt salts, zinc salts, barium salts and lead salts are used.

Examples of the fatty acid esters used include butyl stearate, octyl myristate, monoglyceride stearate, monoglyceride palmitate, and monoglyceride oleate.

As the fatty acid amide, for example, caproic acid amide, lauric acid amide, palmitic acid amide, hehenic acid amide, oleic acid amide, IJ/-luic acid amide, methylene bisstearic acid amide, etc. are used. .

As the aliphatic alcohol, for example, stearyl alcohol, myristyl alcohol, etc. are used.

In addition to this, for example, chlorides such as trimethylstearylammonium chloride and stearoyl chloride, and amines such as stearylamine, stearylamine acetate, and stearylamine hydrochloride can also be used.

As the fluorine-based lubricant, for example, trichlorofluoroethylene, perfluoropolyether, perfluoroalkyl polyether, perfluoroalkyl carboxylic acid, etc. are used. Specific examples of these commercially available products include, for example, Daiflon #20 manufactured by Daikin Co., Ltd.
, Talai Tonx M1 Kuri Tonx H manufactured by DuPont
1 Vydanox AR1 Fomblin Z-I) OL, Z-25.2-1) IAC. Z-1)I
Examples include sQC and Z-AM2001.

As the silicone-based lubricant, for example, /refoon oil, modified silicone oil, etc. are used.

As the hydrocarbon lubricant, for example, paraffin, squalane, wax, etc. are used.

The lubricant is also preferably a nitrogen-containing compound. When a rust preventive agent made of a nitrogen-containing compound and a lubricant are used together, the synergistic effect of these agents improves corrosion resistance in a dramatic manner.

The thickness of the lubricant layer is not particularly limited, but the total thickness including the rust preventive layer is preferably in the range of 50 to 500 layers.

There are no particular restrictions on the method of applying rust preventives and lubricants. Spray, brush, splash, roll coat.

It can be easily printed using any of the known conventional printing methods such as barcode printing, gravure printing, etc. In addition to the above-mentioned direct coating method, an indirect coating method such as a transfer method can also be used.

Since rust inhibitors and lubricants are applied in the form of aqueous solutions, suspensions, etc., the medium must be dried after their application. The drying method is not particularly limited, but drying with hot air or far infrared rays is preferred. Hot air drying is particularly preferred. If the drying temperature is high, the drying time will be shortened and the throughput will be improved, but if the 7i, A degree is too high, it will have an adverse effect on the magnetic recording layer, which is not preferable. A person skilled in the art can easily determine, through repeated experiments, a drying temperature that does not adversely affect the magnetic recording layer and the non-magnetic substrate and also does not lower the throughput.

The magnetic recording medium on which the rust preventive layer has been formed is passed between rotating bodies such as wooden rolls so that the outer circumferential surface of the rotary body is brought into sliding contact with the surface of the ferromagnetic metal thin film, and the rust preventive layer becomes ferromagnetic. Mechanochemically adsorbs onto metal thin film.

When a magnetic recording medium is passed between rolls, the ferromagnetic metal thin film may be damaged by the pushing force generated when the medium passes through the rolls. If such damage occurs in the ferromagnetic metal thin film, it will lead to deterioration of the magnetic properties of the magnetic recording medium. Therefore, in the manufacturing method of the present invention, the outer periphery of the roll that comes into sliding contact with the ferromagnetic metal thin film side of the medium is made of a flexible material to prevent damage to the ferromagnetic metal thin film. The flexible material is, for example, a nonwoven fabric, a fabric, or an elastomer such as rubber or elastic plastic. The outer circumferential surface of the roll is wound with these flexible materials.

The outer periphery of the roll that comes into sliding contact with the back surface of the magnetic recording medium can also be wound with the same flexible material as described above.

The roll may be rolled in - stages, but it can also be rolled in multiple stages if necessary. In the rolling process, the integral conditions (for example, the number of stages for press flange, roll passage time, etc.) can be appropriately determined by evaluating the corrosion resistance, magnetic properties, etc. of the obtained medium.

In the case of a magnetic recording medium in which a lubricant layer is laminated on the rust preventive layer 1-, rolling may or may not be carried out at the time the rust preventive layer is formed; Rolling can also be carried out after laminating the agent layers. This order does not affect the effectiveness of the present invention.

The ferromagnetic metals that can be used to form the ferromagnetic metal thin film of the magnetic recording medium of the present invention are F ez Co 1N + 1, alloys of these, alloys of these 3d transition metals with various principals, or γ-Fe2O3. These are oxides such as , or nitrides.

+Iir The ferromagnetic metal is deposited on the non-magnetic substrate 1 by physical vapor deposition.
- Can be laminated. Physical vapor deposition methods used for manufacturing the magnetic recording medium of the present invention include 1° [air vapor deposition method, ion blating method, sputtering method, ion beam deposition method, and chemical vapor deposition method (CV
D method) etc. Any of these methods can be used in the present invention. The vapor deposition may be either oblique vapor deposition or eastward vapor deposition.

The outer surface of the metal branch r forming the ferromagnetic metal thin film is preferably coated with an oxide film of the metal. The presence of an oxide film enhances the anticorrosion effect.

In particular, when using Co, one of the particles on the ferromagnetic metal thin film side
Near one end, there is a film thickness of 108 to 200 C.

It is preferable to form a passive film. The Co passive state film may be a layer containing an oxide or a hydrated oxide of Co on three sides 1-, for example, Co, ? 04. C.

203, Co30q * r+H20 or Co
Examples include 203·nH2O. In particular, amorphous hydrated oxides have a great anticorrosion effect. The amorphous hydrated oxide layer can be produced by forming a ferromagnetic overlayer and then allowing it to stand for a predetermined period in an oxygen-enriched atmosphere.

As the non-magnetic substrate used in the magnetic recording medium of the present invention, polyimide, polyethylene terephthalate, etc.
hMolecular films, glasses, ceramics, etc.

There are metal plates made of aluminum, anodized aluminum, brass, etc., and Si-medium crystal plates whose surfaces are thermally oxidized.

This non-magnetic substrate is provided with a ground polishing layer such as a full layer or an alumite treatment layer for polishing and texturing, if necessary. You can also do that.

In addition, as magnetic recording media, polyester film,
Magnetic tapes and magnetic disks based on synthetic resin films such as polyimide filtration, disks and drums made of synthetic resin filtration, aluminum plates, glass plates, etc.), magnetic disks and magnetic drums with λ bodies, etc. To magnetism
It encompasses various forms of structures involving 7 and ff2F.

[Example] Hereinafter, the present invention will be explained in detail by way of examples.

A polyethylene terephthalate (PET) film with a thickness of 9 μm was used as the magnetic substrate, and a Co-N1 (composition ratio 80:20) alloy was used as the ferromagnetic metal.
Oxygen atmosphere (Po2 = lx
Vapor deposition was performed to a thickness of 1,500 layers at a pressure of 10-4 Torr.

0.05 wt% methyl isobutyl ketone of 2-nitrosonaphthol (MIBK
) The solution was applied by gravure method and dried with hot air at 80°C. Thereafter, as a lubricant, a 0.05vtX Freon solution under the trade name of Finprin Z-DOL (II Kiso/Technology Co., Ltd.) was applied to the sample 1 in the same manner as above, and dried.

In this way, a rust preventive layer and a lubricant layer having a total thickness of 911 mm and a 200 mm thickness were formed on the magnetic film.

Thereafter, a metal roll rotating at 500 Orpm and having a surface roughness Ra of 0.2 μm was brought into sliding contact with the surface of the original diamagnetic film on which tension was applied. Note that the rotation direction of this roll was made to match the running direction of the tape material.

A magnetic tape was prepared in the same manner as in Example I except that the rust preventive was changed from 2-nitrosonaphthol to 5-nitrobenzotriazole.

Example 11 except that the evaporated original fabric was placed in a vacuum chamber at 20 Torr, and then treated in oxygen at 1 atm for 311 hours to form a cobalt-free MJrs layer on the surface of the magnetic film. A magnetic tape was manufactured in the same manner as in Example 1.

Waterstop 10 - A magnetic tape was produced in the same manner as in Example 1, except that the process of applying the rust preventive layer and lubricant layer and sliding the rotating body into contact after drying was omitted.

Waterstopping 2- A magnetic tape was produced in the same manner as in Example 1 except that the application of the rust preventive agent was omitted.

Water-stopping dmasu J- Example 1 except that the application of rust preventive agent and the sliding contact of the rotating body were omitted.
A magnetic tape was produced in the same manner as above.

An evaluation test was conducted on the corrosion resistance of each magnetic tape obtained as described above. The corrosion resistance value was determined by a popular accelerated test using corrosive gas.

That is, 802 lppm at 35°C and 75% RH.

After exposing each magnetic tape for 100 hours to a medium containing 0.5 ppm of N2S and lppm of NO2, the samples were subjected to XMA analysis (manufactured by Philips, Model AX9100) to determine the content of sulfur in the ferromagnetic metal thin film 2X2 mmZ. (at%), the corrosion resistance of each magnetic tape was determined to be 11·1. The measurement results are shown in Table 1 below.

As is clear from the above results in Table 2, according to the method of the present invention,
The magnetic tape produced by applying the rust preventive agent and obtaining mechanochemical effects (1) has dramatically improved corrosion resistance compared to the tape of the comparative example. Although Fomblin Z-I) OL was used as the lubricant here, by using a lubricant containing nitrogen, the lubricant itself can have a certain degree of rust prevention effect, so due to the synergistic effect, the Corrosion resistance is obtained.

[Effect of the invention] Here it is! -As explained above, according to the manufacturing method of the present invention, a rust preventive agent is applied onto a ferromagnetic metal thin film, and after drying, a rotating body such as a roll is slid on this rust preventive layer 1-. , the rust inhibitor is pressed onto the ferromagnetic metal thin film.

Due to this mechanical step of sliding (in history, there is probably also the effect of M-11ul due to friction during sliding)
, the mechanochemical chemical adsorption of the rust preventive agent has progressed, and the rust preventive molecules, which were originally attached to the ferromagnetic metal thin film 1-, are chemically adsorbed to the ferromagnetic metal thin film 7t, and magnetic recording is now possible. The corrosion protection function of the entire medium is enhanced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a cross-sectional structure of a magnetic recording medium of the present invention, and FIG. 2 is a schematic diagram showing a cross-sectional structure of another magnetic recording medium of the present invention. 1... No. 1 magnetic substrate, 2... ferromagnetic metal thin film. 3... Rust preventive layer, 4... Lubricant layer properties 1; 1 Applicant 11\l Maxell Co., Ltd. Agent Patent Attorney 1- Sen Kaji Yama Kore Patent Attorney 1 Tomi Yamaki [Male]

Claims (8)

[Claims] (1) In a magnetic recording medium in which a ferromagnetic metal thin film layer is provided on a nonmagnetic substrate, at least a rust preventive layer is provided on the surface of the ferromagnetic metal thin film, and then a rotating body is slid onto the ferromagnetic metal thin film surface. A method for manufacturing a magnetic recording medium, characterized in that the magnetic recording medium is brought into contact with the magnetic recording medium. (2) A rotating body is brought into sliding contact with the surface of the ferromagnetic metal thin film after a rust preventive layer is provided on the surface of the ferromagnetic metal thin film and a lubricant layer is further provided thereon. A method of manufacturing the magnetic recording medium described above. (3) Claim 1 or 2, wherein the rust preventive agent and the lubricant are composed of a compound containing a nitrogen atom in the molecule.
The method for manufacturing a magnetic recording medium according to claim 2. (4) The method for manufacturing a magnetic recording medium according to claim 1 or 2, wherein the ferromagnetic metal thin film is made of Co alone or a Co alloy. (5) The method for manufacturing a magnetic recording medium according to claim 4, wherein a Co passive film is formed on the surface of the Co metal particles of the ferromagnetic metal thin film made of Co alone or a Co alloy. (6) The rotary body is brought into sliding contact with the surface of the ferromagnetic metal thin film by passing between two rotary bodies, according to any one of claims 1 to 5. A method for manufacturing a magnetic recording medium. (7) The magnetic recording medium according to any one of claims 1 to 6, wherein the outer peripheral surface of the rotating body that is in sliding contact with the surface of the ferromagnetic metal thin film is made of a soft material. manufacturing method. (8) The method for manufacturing a magnetic recording medium according to claim 7, wherein the soft material is a nonwoven fabric, a woven fabric, or an elastomer.