JPS6050728A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To satisfy the characteristics of wear resistance, running stability and slipperiness and to obtain excellent durability in still reproduction as well by providing an org. layer contg. at least one among aliphat. ketone, aliphat. ether and paraffin and fatty acid amide on a thin ferromagnetic metallic film. CONSTITUTION:A thin ferromagnetic film 2 is formed on the surface of a non- magnetic base 1, and an org. layer 3 contg. fatty acid amide and at least one among aliphat. ketone, aliphat. ether and paraffin is provided on said film 2. The aliphat. ketone is aliphat. ketone having a straight chain alkyl group of >=12 carbon atoms, and the aliphat. ether is aliphat. ether having a straight chain alkyl group of >=12 carbon atoms. The paraffin having >=40 deg.C, more preferably, >=60 deg.C m.p. is effective. The fatty acid amide is preferably an acid amide consisting of a fatty acid having >=12 carbon atoms, more particularly a fatty acid having >=22 carbon atoms.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a ferromagnetic thin film type magnetic recording medium that is excellent in high-density recording.

Configuration of conventional example and its problems Conventional γ-Fe203. co-containing γ-Fe2o3°C
Ferromagnetic powder of rO2 is dispersed and applied in an organic binder. In place of so-called coating-type magnetic recording media, ferromagnetic metal thin films formed by methods such as plating, sputtering, vacuum evaporation, and ion blating are being considered as magnetic recording media for high-density recording, and are being used for audio applications. has already been put into practical use.

However, major problems with magnetic recording media using ferromagnetic metal thin films are their wear resistance, running stability, flexibility, slipperiness, and durability for still playback.

38-. That is, the magnetic recording medium is subjected to high-speed relative motion with the magnetic head during the process of recording and reproducing magnetic signals. In this case, the vehicle must run smoothly and stably. Furthermore, there must be no wear, damage, or scratches due to contact with the magnetic head.

However, the ferromagnetic metal thin film layer alone cannot withstand the harsh conditions during magnetic recording and reproduction; (80%) - Nickel (20%) ferromagnetic metal thin film will run unstable due to friction with the magnetic head, and if it is run for a long time, it will wear out or break. In some cases, output may drop significantly due to wear particles. especially,
In still playback, it lacked durability, with scratches appearing on the magnetic surface within one minute, resulting in a significant drop in output. Therefore, it has been proposed in the past to provide various slippery layers on the surface layer, such as a method of providing a saturated fatty acid or a metal salt thereof (
Publication No. 56-30609 Publication No. 56-30609 Publication No. 56-30609 Publication No.
), but this method does not improve running stability, wear resistance,
Although the lubricity was improved to some extent, there was almost no durability in still playback.

Purpose of the Invention The object of the present invention is to provide a metal thin film type magnetic recording medium that satisfies the characteristics of wear resistance, running stability, and lubricity, and has excellent one-sided durability in still playback. It is something.

Structure of the Invention The magnetic recording medium of the present invention includes a ferromagnetic metal thin film provided on the surface of a nonmagnetic substrate, and at least one of an aliphatic ketone, an aliphatic ether, and a paraffin and a fatty acid amide on the ferromagnetic metal thin film. It has a structure with an organic layer that contains fatty acid amide and the above compounds (aliphatic ketone, aliphatic ether, paraffin) to improve lubricity and improve the protective properties of the ferromagnetic metal thin film, resulting in wear resistance. It satisfies the properties of performance, running stability, and slipperiness, and has excellent still playback durability.

Description of Embodiments 5,・The following embodiments of the present invention will be described below with reference to the drawings.i)
1. I will clarify.

The drawing is an enlarged sectional view showing an example of the magnetic recording medium of the present invention. In the drawing, 1 is a non-magnetic substrate such as a polyethylene terephthalate film, and this non-magnetic substrate 10
A ferromagnetic metal thin film 2 is formed on the surface, and an organic layer 3 containing a fatty acid amide and at least one of aliphatic ketones, aliphatic ethers, and paraffins is provided on the ferromagnetic metal thin film 2.

The aliphatic ketones used in this invention are aliphatic ketones having an IL 1-chain alkyl group having 12 or more carbon atoms, such as cytodecyl ketone, ditetradefluketone, dihexadecyl ketone, dioctadecyl ketone, and jacosyl ketone. , dilauryl ketone.

Examples include didodecyl ether. With aliphatic ketones having a straight chain alkyl group having only 11 or less carbon atoms, there remains concern about the durability of still regeneration.

The aliphatic ether used in this invention has 6 carbon atoms,
.

an aliphatic ether having 12 or more straight-chain alkyl groups,
For example, didodecyl ether, ditetradecyl ether, dihexadecyl ether, dioctadecyl ether, dilauryl ether, dieicosyl ether, didocosyl ether, etc.! :I can do it for you. Number of carbons is 1
For aliphatic ethers having only one or less linear alkyl groups, there remains concern about the durability of still regeneration.

The paraffin used in this invention is effective if it has a melting point of 40"C or higher, preferably 60"C or higher.

If the melting point is below 40°C, there is concern about the durability of still regeneration.〇The fatty acid amide used in this invention is a fatty acid with a carbon number of 1.
Among them, amides consisting of two or more fatty acids, particularly those having 22 or more carbon atoms, are preferable, such as behenic acid amide, lignoceric acid amide, cerotinic acid amide, etc. With fatty acid amides having 11 or fewer carbon atoms, there remains concern about the durability of still regeneration.

Aliphatic T thioethers can also be used as the aliphatic ethers used in this invention. This aliphatic thioether is an aliphatic thioether having a linear alkyl group having 12 or more carbon atoms, such as didodecyl thioether,
Ditetradecyl thioether.

Examples include dihexadene thioether, dioctadecyl thioether, dieicosyl thioether, dilauryl thioether, didodecyl thioether, etc.
Ru. In the case of an aliphatic thioether having a straight chain alkyl group having only 11 or less carbon atoms, there remains concern about the durability of still regeneration.

The 41 layers of 3 layers in this invention can be formed by a wet method or a dry method. Further, when the magnetic Ha recording medium is in the form of a tape, the organic layer 3 is provided on the back surface of the non-magnetic substrate 1 in advance, and when the tape is rolled up, the organic layer 3 is placed on the surface of the ferromagnetic metal thin film 2. Known methods such as a method of making the image transcribe can be used.

Dry methods include Qi and I1 machine deposition methods, and wet methods include rod coating method, gravure method, reverse roll method, doctor knife method, etc.

JP-A-Sho GG-50728 (3) Solvents for the coating solution used in the wet method include benzene, toluene, xylene, methanol, ethanol, propatool, acetone, fatty acid amides such as methyl ethyl ketone,
Any solvent can be used as long as it dissolves aliphatic ketones, aliphatic ethers, and paraffins (mixed solvents are also acceptable). When the organic layer 3 of the present invention is provided on the surface of the ferromagnetic metal thin film 20 by a wet method. The concentration of fatty acid amide, aliphatic ketone, etc. in the coating solution is about 1% by weight to 0.005%.
Weight %, preferably in the range 0.5% to 0.01% by weight, is suitable. If the concentration of fatty acid amide, etc. is higher than 1% by weight, when applied to the ferromagnetic metal thin film 2, it will precipitate in the form of lumps large enough to be seen with the naked eye, which will only reduce the durability of still playback. This results in a decrease in output due to so-called spacing loss.

The ferromagnetic metal thin film 2 in this invention is a thin film made of ferromagnetic metals such as cobalt and nickel or their alloys by vacuum evaporation, etc., and for use in magnetic recording media, it is suitable for use in magnetic recording media. The film thickness is approximately 100 μm (d, 500 to 5000 people).

Hereinafter, implementation of the present invention will be described in further detail.

Example: Cobalt (80%) - Nickel (20%) was deposited on a 10 μm thick polyethylene terephthalate film (hereinafter referred to as PET film) by vacuum deposition method.
A ferromagnetic metal thin film (thickness: 10 μm) was fabricated by continuous oblique evaporation with forced introduction of oxygen. On this ferromagnetic metal thin film, coating solutions 1 to 2 having the following compositions were applied as an organic layer by a rod coating method. After coating, the tapes were cut into widths of 81 ul to obtain 8 types of magnetic tapes. The coefficient of dynamic friction was measured in an environment of 26°C and 6Q% iron. Here, a magnetic tape formed using coating liquid i was used as Example 1, a magnetic tape formed using coating liquid ■ was prepared as Example 2, a magnetic tape formed using coating liquid ■ was prepared as Example 3, and a magnetic tape formed using coating liquid ■ was prepared as Example 3. Magnetic tape 4 formed using ■Example 4, magnetic tape formed using coating liquid ■.Example 5, magnetic tape formed using coating liquid ■. tape 4・
A magnetic tape formed using Example 7 and coating liquid (2) is referred to as Example 8. In addition, a certain video signal was recorded on these magnetic tapes in an environment of 26 TE, e o% RH using a testing machine with the same functions as a commercially available video tape recorder, and the reproduced still images were determined to be magnetic. The time required for scratches to disappear due to the occurrence of scratches on the surface was measured. Table 1 shows the measurement results of each methyl property and coefficient of dynamic friction.

Comparative example: A ferromagnetic thin film was formed on each PET film in the same manner as in the previous example, and coating liquids ■ to X■ having the following compositions were further applied thereon. , L. Luen 10009 After coating, the magnetic tapes were cut into 8-inch widths to obtain 9 types of magnetic tapes.

Comparative Example 1 is a magnetic tape formed using coating liquid ■, Comparative Example 4 is a magnetic tape formed using coating liquid X, Comparative Example 2 is a magnetic tape formed using coating liquid M, and Comparative Example 3 is a magnetic tape formed using coating liquid M.
Comparative Example 4, a magnetic tape formed with coating liquid ■, Comparative Example 5, a magnetic tape formed with coating liquid xnI, Comparative Example 6, a magnetic tape formed with coating liquid W, and a comparison of magnetic tape formed with coating liquid Xv. Comparative Example 8 is a magnetic tape formed using Example 7 and coating liquid (1), and Comparative Example 9 is a magnetic tape formed using a coating liquid reservoir. Furthermore, a magnetic tape obtained under the same conditions without applying a coating liquid was designated as Comparative Example 10.

The coefficient of kinetic friction of these magnetic tapes is i25”c, 60%R
Measurements were made under H environment. In addition, under the same environment, a certain video signal was recorded using a testing machine with these magnetic functions, and the reproduced still image showed that the scratches occurred on the magnetic surface.
The time it took for it to disappear and evaporate was measured.

Table 2 shows the measurement results of each still characteristic and dynamic friction coefficient.

(Margins below) 15/-- Table 2 As can be seen from Tables 1 and 2, the magnetic tapes obtained in Examples 1 to 8 were heated at 25°C and eoRH. −
50728 (5) Excellent durability of still regeneration at room temperature and normal temperature, low coefficient of dynamic friction not only at initial stage but also after 100 reciprocations, excellent in slipperiness, wear resistance, and running stability. I understand that.

When these magnetic tapes were run repeatedly in an atmosphere of 40°C and 280% RH in a testing machine with the same functionality as a commercially available video tape recorder, the magnetic tapes of Examples 1 to 8 continued to run even after 100 hours. On the other hand, the magnetic tapes obtained in Comparative Examples 1 to 10 ran unstable, and tape wear was observed.

In the above description, the magnetic tape has been described, but the present invention can also be applied to magnetic disks, magnetic cards, etc.

Effects of the Invention As described above, the magnetic recording medium of the present invention has excellent wear resistance by providing an organic layer containing at least one of an aliphatic ketone, an aliphatic ether, and a paraffin and a fatty acid amide on a ferromagnetic metal thin film. It satisfies the characteristics of stability, running stability, and slipperiness, and has excellent regeneration durability, and its practical effects are amazing.

[Brief explanation of the drawing]

Drawing←1: It is an enlarged sectional view of the magnetic recording medium of this invention. 1...Nonmagnetic substrate, 2...Ferromagnetic metal thin film, 3
...Organic layer.

Claims (6)

[Claims] (1) A nonmagnetic substrate, a ferromagnetic metal thin film provided on the surface of the nonmagnetic substrate, and at least one of aliphatic ketone, aliphatic ether, and paraffin and fatty acid amide provided on the ferromagnetic metal thin film. 1. A magnetic recording medium comprising: 41 layers containing 41 layers. (2) The magnetic recording medium according to claim 1, wherein the aliphatic ketone is an aliphatic ketone having a linear alkyl group having 12 or more carbon atoms. (3) The magnetic recording medium according to claim 1, wherein the aliphatic ether is an aliphatic ether having a linear alkyl group having 12 or more carbon atoms. (4) The magnetic recording medium according to claim 1, wherein the halafin is paraffin having a melting point of 40°C or higher. (5) The magnetic recording medium according to claim 1, wherein the fatty acid amide is an amide of a fatty acid having 12 or more carbon atoms. (6) The magnetic recording medium according to claim 3, wherein the aliphatic ether is an aliphatic ether containing an aliphatic thioether.