JPS63191313A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability and corrosion resistance without deteriorating an electromagnetic conversion characteristic by forming a thin ferromagnetic metallic film layer consisting of a metal or the alloy thereof on a substrate and providing a protective film layer consisting of any one among Cr, Mn and Al, and Ni and O on the surface thereof. CONSTITUTION:A polyester film 1 having 9mum thickness is loaded into a vacuum deposition device and after the inside of the vessel is evacuated to 5X10<-5>Torr vacuum, gaseous oxygen is introduced into the vessel to 8X10<-5> and cobalt is heated to evaporate and the vapor thereof is deposited by evaporation diagonally on the film 1 at 100Angstrom /sec deposition rate to form the thin ferromagnetic metallic film 2 layer consisting of the cobalt contg. oxygen to 1,500Angstrom thickness on said film. The inside of the vessel is then evacuated to 5X10<-6>Torr vacuum and thereafter, the gaseous oxygen is introduced into the vessel at variously varied ratios. An Ni-Cr alloy is heated to evaporate and the vapor thereof is deposited by evaporation diagonally onto the above-mentioned film at various deposition rates to form the protective film layer 3 having various compsns. consisting of Ni and Cr and O to 200Angstrom thickness. A 0.1wt.% methyl isobutyl ketone soln. of stearic acid is then coated on the layer 3 and is dried to form a lubricating agent layer 4 consisting of the stearic acid and having 10Angstrom thickness on said layer. The tape is cut to a prescribed width, by which a magnetic tape A is obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer, and more particularly relates to the above-mentioned magnetic recording medium having excellent durability and corrosion resistance. .

[Conventional technology]

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal i-film layer is
It is usually made by depositing metals or their alloys on a base film by vacuum deposition, sputtering, etc., and has characteristics suitable for high-density recording, but on the other hand, the coefficient of friction with the magnetic head is high, causing wear and damage. It is easily susceptible to corrosion, and is corroded by moisture in the atmosphere and corrosive gases such as SO2 gas and NO2 gas, resulting in a decrease in saturation magnetization.
Furthermore, there are other drawbacks such as corrosion products that impede running performance.

For this reason, various protective film layers have been conventionally provided on the ferromagnetic metal thin film layer to improve durability and corrosion resistance. For example, metal thin film layers made of Ti, Cr, Nl, etc. (Japanese Unexamined Patent Publication No. 58-2632)
No. 0, JP-A-58-108030, JP-A-53-72
05), a non-magnetic alloy thin film layer of Ni-Cr (Japanese Patent Application Laid-Open No. 73108/1982), and an amorphous hydrated oxide layer of trivalent or higher Co (Japanese Patent Application Laid-Open No. 60/1989). Attempts have been made to improve durability and corrosion resistance by forming a hydrated chromium oxyhydroxide layer (Japanese Unexamined Patent Publication No. 17356/1983).

[Problem that the invention seeks to solve]

However, those with a metal thin film layer made of Ti or Cr cannot sufficiently improve durability, and there is a problem that electromagnetic conversion characteristics deteriorate when the thickness of the metal thin film layer is increased. Those with a metal thin film layer are
Since it has magnetism, there is no deterioration of electromagnetic conversion characteristics ζ,
Durability and corrosion resistance cannot be sufficiently improved.

Furthermore, products with Ni-Cr non-magnetic alloy thin film layers have the problem of deteriorating electromagnetic conversion characteristics because they are non-magnetic, and if the Cr content is increased to improve corrosion resistance, durability deteriorates. There is a drawback. Further C
Although corrosion due to moisture in the atmosphere can be effectively prevented by forming an amorphous hydrated oxide layer with a valence of 3 or higher or a hydrated chromium oxyhydroxide layer on the surface of a ferromagnetic metal thin film layer, S02 Corrosion resistance against corrosive gases such as gas and NO2 gas cannot be sufficiently improved.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation.
By providing a protective film layer consisting of any one selected from 1, Ni, and 0, the durability is sufficiently improved without deteriorating the electromagnetic conversion characteristics, and it is able to withstand moisture in the atmosphere, S02 gas, It has sufficiently improved corrosion resistance against corrosive gases such as N02 gas. Further, by further providing a lubricant layer on these protective film layers, wear resistance is further improved, and durability and corrosion resistance are further improved.

In this invention, the protective film layer formed on the ferromagnetic metal thin film layer is made of Ni-Cr alloy, Ni-Mn alloy, Ni-
CrSM is formed by depositing Al alloy etc. on a ferromagnetic metal thin film layer by oblique incidence evaporation method in the presence of oxygen gas.
A protective film layer is formed of an aggregate of diagonally inclined columnar particles made of one selected from n5Al, Ni, and 0.

This type of protective film layer formed in this way has an atomic ratio of oxygen atoms to all constituent atoms of the protective film layer (0/(N
i +Cr +O), O/ (Ni +Mn+O
), O/ (Ni+Al+O)) are both 0.2
~0.45, and the atomic ratio of Cr to Ni (Cr/Ni) is within the range of 0.05 to 0.5, M
The atomic ratio of n to Ni (Mn/Ni) is 0.05 to 0
．． Within the range of 3, the atomic ratio of Al to Ni (Al/Ni
) is preferably within the range of 0.01 to 0.3,
The atomic ratio of oxygen atoms to all constituent atoms of the protective film layer is 0.
If it is smaller than 2, durability cannot be sufficiently improved, and if it is larger than 0.45, there will be too much non-magnetic component, making it impossible to prevent deterioration of electromagnetic conversion characteristics. Further, if the atomic ratio of Cr to Nt is smaller than 0.05, sufficient corrosion resistance cannot be obtained, and if it is larger than 0.5, durability deteriorates. Similarly, the atomic ratio of Mn to Ni is 0.0
If it is smaller than 5, sufficient corrosion resistance cannot be obtained, and if it is larger than 0.3, corrosion resistance and durability deteriorate, and furthermore, Al
If the atomic ratio of Ni to Ni is less than 0.01, sufficient corrosion resistance will not be obtained, and if it is greater than 0.3, both corrosion resistance and durability will deteriorate. The protective film layer preferably has a coercive force of 100 Oe or more, and if the atomic ratio of Ni to Cr*Mn+Al is lower than the above range, the nonmagnetic component of the protective film layer will increase. If this happens too much, it becomes impossible to prevent deterioration of the electromagnetic conversion characteristics.

In this way, this type of protective film layer formed of one selected from Cr s M n SA l, Ni, and 0 has magnetism and electromagnetic conversion characteristics because it contains unoxidized Ni. The protective film layer made of Ni, Cr, and 0 will not deteriorate, and the durability can be sufficiently improved by the Ni oxide present in the protective film layer, and the durability can be sufficiently improved by the Cr oxide. Provides corrosion resistance. Similarly, Ni and M
The protective film layer consisting of n and 0 is composed of N present in the protective film layer.
The durability can be sufficiently improved by the oxide of i, and at the same time, the oxidation of Ni is promoted by Mn, so that some of the Ni oxides have higher valence than Ni2O3 or Ni30.
4, and the corrosion resistance of NiO to corrosive gases is improved, so the corrosion resistance to corrosive gases is improved. Furthermore, the durability of the protective film layer consisting of Ni, Al, and 0 can be sufficiently improved by the Ni oxide present in the protective film layer, and at the same time, Al exists as Al2O3 and Ni
Since a dense film with a spinel structure is formed with O, reduction of NiO by corrosive gas can be prevented and corrosion resistance can be sufficiently improved.

In addition, this protective film layer further improves the durability described above by being composed of an aggregate of diagonally inclined columnar particles consisting of one selected from Cr, Mn SA 1, Ni, and 0. At the same time, deterioration of electromagnetic conversion characteristics can be prevented.

The thickness of such a protective film layer is preferably within the range of 50 to 1,000 layers; if it is thinner than 50 layers, the desired effect will not be obtained, and if it is thicker than 1,000 layers, the spacing loss will increase. There is a risk that the electromagnetic conversion characteristics will deteriorate.

In this way, Cr s M n,
If a protective film layer is formed of one selected from Al, Ni, and 0, the electromagnetic conversion characteristics will not deteriorate and the durability and corrosion resistance will be sufficiently improved. In addition, when a lubricant layer is further formed, the lubricating effect of the lubricant layer is fully exhibited, the coefficient of friction is sufficiently reduced, and the wear resistance is further improved.

Such a lubricant layer is prepared by dissolving a lubricant in a suitable solvent such as toluene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, ethyl acetate, tetrahydrofuran, dimethylformamide, dioxane, etc., and adding the above-mentioned lubricant to the solution obtained by dissolving it. The lubricant can be formed by dipping the protective film layer, or by coating or spraying this solution on the protective film layer, or by vacuum-depositing a lubricant onto the protective film layer. It is formed. When a lubricant layer is formed on the above-mentioned protective film layer in this way, the lubricating effect of the lubricant layer is fully exhibited, the coefficient of friction is sufficiently reduced, and the wear resistance is further improved. .

Suitable lubricants used include aliphatic lubricants, fluorine-based lubricants, silicone-based lubricants, and hydrocarbon-based lubricants. Examples of aliphatic lubricants include fatty acids, fatty acid metal salts, fatty acid esters,
Fatty acid amides, aliphatic alcohols, etc. are used. Preferred fatty acids include lauric acid, myristic acid, valmitic acid, stearic acid, and behenic acid.
As metal salts of fatty acids, magnesium salts, aluminum salts, lithium salts, sodium salts, calcium salts, cobalt salts, zinc salts, barium salts, lead salts, etc. of these fats are preferably used. In addition, fatty acid esters include butyl stearate, octyl myristate, stearic acid monoglyceride, valmitic acid monoglyceride,
Oleic acid monoglyceride and the like are preferably used, and as the fatty acid amide, caproic acid amide, capric acid amide, lauric acid amide, valmitic acid amide, behenic acid amide, oleic acid amide, linoleic acid amide, methylene bisstearic acid amide, etc. are preferable. used. Further, as the aliphatic alcohol, stearyl alcohol, myristyl alcohol, etc. are preferably used.
In addition, chlorides such as trimethylstearylammonium chloride and stearoyl monide, and amines such as stearylamine, stearylamine acetate, and stearylamine hydrochloride are also used.

In addition, as the fluorine-based lubricant, trichlorofluoroethylene, perfluoropolyether, perfluoroalkyl polyether, perfluoroalkyl carboxylic acid, etc. are preferably used, and specific examples of commercially available products include Guyfroil # manufactured by Daikin Corporation. 20, DuPont Tallite Fuchs M, Kreit Fuchs H, Paida Sox AR,
Examples include Fomblin 2 manufactured by Montegisson. Furthermore, examples of the silicone lubricant include silicone oil and modified silicone oil, and examples of the hydrocarbon lubricant include paraffin, squalane, wax, and the like.

In addition, the lubricant layer formed using these lubricants may be composed only of these lubricants, or may contain a rust preventive agent and fine particles. As a rust preventive agent, butylhydroxyanisole, butylhydroxyanisole, Dibutylhydroxytoluene, benzotriazole, benzotriazole laurylamine, hydroquinone, dimethylaminoethyl methacrylate, triphenyl phosphite, tridecyl phosphite, trilauryl thiophosphite, butyl phosphate, dilauryl thiodipropionate, sorbitol, propylene glycol, Phenol-based, amine-based, phosphorus-based, sulfur-based, organic acid-based, and quinone-based rust inhibitors such as hydroquinone are preferably used. In addition, as fine particles,
A1203, ZrO2, Cr203, Fe304,
Fe2 o3, TiO2, SiO□, SnO2, etc. are preferably used.

The thickness of the lubricant layer formed using such a lubricant is preferably 20 Å or more in order to sufficiently exhibit the lubricating effect and sufficiently improve wear resistance. However, if the total thickness of the ferromagnetic metal thin film layer and the protective film layer laminated on the ferromagnetic metal thin film layer becomes thicker than 1000, the spacing loss may increase and the electromagnetic conversion characteristics may deteriorate. It is preferable that the total thickness of the layers is 1000 Å or less.

The material for forming the ferromagnetic metal thin film layer is Co.

Metals such as Fe*N1, co-Ni, Co-Cr
.

Fe-Go, Fe-Go-Cr, Co-Pt, C0-T
ferromagnetic metal thin film layers made of these ferromagnetic materials are formed by vacuum deposition. , ion blasting, sputtering, plating, etc., on the substrate.

In addition, as a substrate, plastic films such as polyester, polyimide, polyamide, polyvinyl chloride, and polycarbonate, composite films in which carbon fiber, Cu silicon, etc. are mixed or coated with these plastic films, and Cu t Zn etc. Conventionally used materials such as non-magnetic metal films, aluminum plates, and glass plates are all suitable.

Magnetic recording media include various types of magnetic recording media that have a structure that makes sliding contact with a magnetic head, such as magnetic tapes using plastic films as bases, magnetic disks and magnetic drums using disks made of plastic films, aluminum plates, glass plates, etc. as bases. Includes form.

〔Example〕

Next, embodiments of the invention will be described.

Examples 1 to 10 A polyester film with a thickness of 9 μm was placed in a vacuum evaporation device, and after evacuating to 5×10 torr, oxygen gas was introduced to make the film 8×10″5), and cobalt was heated to evaporate. , a ferromagnetic metal thin film layer consisting of cobalt containing oxygen was formed on the polyester film with a thickness of 1500 people/sec by oblique incidence deposition at a deposition rate of 100 people/sec.Then, it was evacuated to 5 x 10-6 Torr. After that, oxygen gas was introduced at various amounts to heat and evaporate the Ni-Cr alloy, and oblique incidence deposition was performed at various deposition rates to obtain a thickness of 2.
00 people formed protective film layers of various compositions consisting of Ni, Cr, and 0. Next, a 0.1% by weight solution of stearic acid in methyl isobutyl ketone is applied onto this protective film layer made of Nt, Cr, and O, and dried to form a lubricant layer of 100% by weight made of stearic acid. was formed. Thereafter, a magnetic tape A was prepared by cutting a predetermined width and sequentially laminating a ferromagnetic metal thin film layer 2, a protective film layer 3, and a lubricant layer 4 on a polyester film 1 as shown in FIG. Ta.

Examples 11 to 20 In Examples 1 to 1O, the same procedure as Examples 1 to 10 was carried out except that the formation of the lubricant layer made of stearic acid was omitted, and on the polyester film 1 as shown in FIG. 2, A magnetic tape B was prepared by sequentially laminating a ferromagnetic metal thin film layer 2 and a protective film layer 3.

Examples 21 to 29 In the formation of the protective film layer in Examples 1 to 10, Ni
The thickness of Ni, Mn, and O was 200, and the content of oxygen and Ni, Mn, and
A protective film layer having various compositions is formed, and magnetic tape A
I made it.

Examples 30 to 38 Magnetic tapes B were produced in the same manner as in Examples 21 to 29, except that the formation of the lubricant layer made of stearic acid was omitted.

Examples 39 to 47 In the formation of the protective film layer in Examples 1 to 10, Ni
The thickness of Ni, Al and 0 was 200 in the same manner as in Examples 1 to 106 except that a Ni-Al alloy was used instead of the -Cr alloy, and the oxygen content and the content of Ni, Al and 0 were Magnetic tape A was produced by forming protective film layers having various compositions.

Examples 48-56 Magnetic tape B was produced in the same manner as in Examples 39-47, except that the formation of the lubricant layer made of stearic acid was omitted.

Comparative Examples 1 to 3 In the formation of the protective film layer in Examples 1 to 10, Ni
-Examples 1 to 1 except that Ni was used instead of the Cr alloy
Similarly to 0, the thickness of Ni and 0 is 200,
Magnetic tapes were produced by forming protective film layers with various oxygen contents.

Comparative Examples 4 to 5 In the formation of the protective film layer in Examples 1 to 1O, the thickness of Ni and Cr was 200, and the thickness of Ni and Cr was 200, except that the introduction of oxygen gas was omitted. A magnetic tape was produced by forming protective film layers with different Cr compositions.

Comparative Examples 6-8 In forming the protective film layer in Examples 11-20, N
Example 1 except that Ni was used in place of the i-Cr alloy.
Similarly to 1 to 20, the thickness of Ni and O is 200.
In humans, protective film layers with various oxygen contents are formed,
I made magnetic tape.

Comparative Examples 9 to 10 In the formation of the protective film layer in Examples 11 to 20, the thickness of Ni and Cr was 200 mm, except that the introduction of oxygen gas was omitted. and C
Protective film layers having different compositions of r were formed to produce magnetic tapes.

Comparative Example 11 A magnetic tape was produced in the same manner as in Example 1 except that the formation of the protective film layer was omitted.

Comparative Examples 1 and 2 A magnetic tape was produced in the same manner as in Example 1, except that the formation of the protective film layer and lubricant layer was omitted.

Regarding the magnetic tapes obtained in each example and comparative example,
The composition of the protective film layer was measured. For this measurement, analysis in the depth direction was performed using Auger electron spectroscopy, and the average was determined.

Further, the coercive force of each magnetic tape was measured, and the output was measured by recording and reproducing using a commercially available VTR deck, and evaluation was made using the magnetic tape obtained in Comparative Example 12 as a reference.

Further, the durability was investigated by measuring the still life during playback under conditions of 40° C. and 80% RH. Also, high temperature and humidity test when the obtained magnetic tape was left under conditions of 60 ° C. and 90% RH for one week, 1.01) PIIS 02, 0.5 pI
) IllHx S, 1.0 ppm NO2, 35°C, 7
A corrosive gas test was conducted when the magnetic tape was left standing for 24 hours in an atmosphere of 5% RH, and the maximum magnetic flux density was measured and expressed as a deterioration rate with respect to the maximum magnetic flux density of the magnetic tape before being left standing. In addition, the surface is observed using an optical microscope, and if there are no corrosion points at all (
O), cases where there were slight corrosion points were evaluated as (Δ), and cases where corrosion was clearly observed were evaluated as (×).

Tables 1 to 3 below show the results.

〔Effect of the invention〕

As is clear from Tables 1 to 3 above, the magnetic tapes obtained in Examples 1 to 56 were
Compared to the magnetic tape obtained by this invention, the coercive force is almost the same, the still playback life is longer, the deterioration rate is small, and corrosion is not observed much by observation. Therefore, the magnetic recording medium obtained by this invention is It can be seen that the electromagnetic conversion characteristics are good, and the durability and corrosion resistance are sufficiently improved.

[Brief explanation of the drawing]

FIGS. 1 and 2 are partially enlarged sectional views of a magnetic tape obtained according to the present invention. 1... Polyester film (substrate), 2... Ferromagnetic metal thin film layer, 3... Protective film layer, 4... Lubricant layer,
A, B...Magnetic tape (magnetic recording medium) patent applicant
Hitachi Maxell Ltd. Figure 1 Figure 2 Figure 1 Polyester film

Claims (1)

[Claims] 1. A ferromagnetic metal thin film layer made of metal or an alloy thereof is formed on a substrate, and on the surface of this ferromagnetic metal thin film layer,
A magnetic recording medium 2 characterized by having a protective film layer made of one selected from Cr, Mn, and Al, Ni, and O, wherein the protective film layer is one selected from Cr, Mn, and Al. A magnetic recording medium 3 according to claim 1, which is constituted by an aggregate of diagonally inclined columnar particles made of one of the above, Ni, and O; A magnetic metal thin film layer is formed, and on the surface of this ferromagnetic metal thin film layer,
Magnetic recording medium 4, protection, characterized in that a protective film layer made of one selected from Cr, Mn, and Al, Ni, and O is provided, and a lubricant layer is further provided on this protective film layer. The magnetic recording medium according to claim 3, wherein the film layer is composed of an aggregate of diagonally inclined columnar particles made of one selected from Cr, Mn, and Al, Ni, and O.