JPS6284429A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance, running property, and durability by providing a combination of fatty acid soap and phosphate to the layer surface of a magnetic recording medium. CONSTITUTION:A combination of the fatty acid soap and phosphate is provided to the layer surface of the magnetic recording medium. This compsn. is applicable to either of a coating type consisting in applying a magnetic coating compd. prepd. by incorporating magnetic powder, etc., in to a binder on a substrate and to a thin film type magnetic recording medium to be formed by directly providing a thin ferromagnetic metallic film on the substrate by a method such as vapor deposition. The effect thereof is remarkable with the thin film type. The total amt. of the compsn. to be applied to the layer surface is 0.5-30mg/m<2>, more preferably 1-10mg/m<2>. The film thickness is preferably 50-500Angstrom in the case of using the coating compd. as an overcoat layer such as lubricating layer and rust preventive layer on the surface layer. The coating compd. consists of an org. solvent soln. contg. 0.05-1wt% mixture composed of the above-mentioned compd. The coefft. of friction is thereby decreased, the running property is improved and the still durability and repetitive durability are remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media, and more specifically to magnetic tapes.

[Prior art]

Magnetic recording media such as magnetic tape, magnetic sheets, and magnetic disks are widely used in the audio, video, and computer fields. For example, magnetic tapes have been of the coated type in which ferromagnetic powder is dispersed in a binder, but as the demand for high-density recording has recently increased, the recording density of this coated type has become smaller due to the binder. Instead, thin-film magnetic recording media, which have a large saturation magnetization and can form a ferromagnetic metal thin film on a support by direct vapor deposition, sputtering, ion blating, etc. without the need for a binder, have come into widespread use. Ta.

However, the ferromagnetic layer of such a thin film type recording medium has a large coefficient of friction, so when it is run on, for example, a video deck, it may be rubbed by a magnetic head, producing a frictional noise called tape squeal. When this friction is severe, the tape may stop. Not only does it have poor running properties, but it is also prone to scratches due to friction with magnetic heads, guide rollers, liners, etc.

For this reason, the so-called still durability, which is when playing a videotape on a deck to view still images, and the so-called repeat durability, which is looking at the durability of playing this tape repeatedly, are significantly inferior to those of the coated type, making it impractical for practical use. The current situation is that it cannot withstand it sufficiently. Furthermore, when the metal thin film is exposed to air, the metal is oxidized by the presence of oxygen and moisture, resulting in poor corrosion resistance. For example, iron oxide (i
'Magnetic Tt Bald? , f! ＜、、F Riso Sengo is a record as a recording medium.

In addition to reducing the needle density, these corroded or scratched areas can also cause noise.

In order to solve these problems, a coating film is provided on the ferromagnetic metal thin film, but in this case, it is necessary to reduce the so-called spacing loss that accompanies the loss of output when scanning the magnetic layer with a magnetic head. Therefore, it is necessary to reduce the film thickness.

In order to solve these problems, conventional methods have been to attach or overcoat various inorganic or organic compounds to the surface of the magnetic layer. For example, JP-A-56-1
No. 43,540 discloses a magnetic recording medium in which a metal thin film layer is provided with a layer mainly composed of polyurethane resin. Furthermore, Japanese Patent Laid-Open No. 133631/1983 discloses a magnetic recording medium in which a sorbitan ester is deposited on a metal thin film layer. However, these are not yet sufficiently durable for practical use, especially when rubbed by a magnetic head. Furthermore, Japanese Patent Application Laid-Open No. 146627/1983 discloses a magnetic recording medium in which a surface treatment film made of phosphate ester or its metal salt is provided on a metal thin film. The invention also states that gold R salts of phosphoric acid esters are preferred.

However, even with this metal salt of phosphoric acid ester, durability such as the above-mentioned tape squeaking and still durability is not sufficient. In particular, recent trends in magnetic recording technology include a shift from compact cassettes to microcassettes in the audio tape field, and a shift from the current VHS and β formats to 8mm video and electronic cameras in the video field. As magnetic tape is becoming more compact and denser, for example, the tape route is becoming more complex, causing contact with guide poles, guide rollers, etc. As the number of opportunities and frequency of abrasion increases, further improvements in mechanical properties such as runnability and durability are desired, and the metal salts of phosphoric acid esters described in "2" cannot satisfy the practicality.

Furthermore, JP-A No. 60-85472 describes trialkyl phosphate esters of alcohols having 10 or more carbon atoms that meet the above requirements, and this material significantly improves running performance and durability. However, for practical purposes, further improvement is desirable.

For these reasons, it has been desired to develop a magnetic recording medium that has corrosion resistance, runnability, and durability that meet recent demands.

[Purpose of the invention]

An object of the present invention is to provide a magnetic recording medium that is corrosion resistant and has good running properties and durability in accordance with the above-mentioned demands.

[Structure of the invention]

The above object of the present invention is achieved by a magnetic recording medium characterized by having a combination of a fatty acid soap and a phosphoric acid ester on the layer surface of the magnetic recording medium.

The combination composition of the fatty acid soap and the phosphoric acid ester comprises:
It can be applied to both coating-type magnetic recording media in which a magnetic paint containing magnetic powder or the like in a binder is applied onto a support, and thin-film magnetic recording media in which a ferromagnetic metal thin film is directly deposited on a support by a method such as vapor deposition. The effect is remarkable in the thin film type.

Furthermore, it may be applied to the layer surface of a back coat layer containing a nonmagnetic filler.

The fatty acid soap according to the present invention is most preferably a cobalt soap.

Examples of fatty acid soaps and phosphoric esters of the present invention are shown below.

(Exemplary fatty acid soap) Cobalt stearate Cobalt laurate Cobalt myristate Cobalt balmitate (Exemplary phosphoric acid ester) (C1aHssO)a PO (CI?H350)3 PO (CI2H□ao)a PO (C+++Hs70)a PO (C1aHssO) s PO (C14H290) s 3PO When the above compound is applied to the layer surface on the magnetic layer side, and if necessary, -6= further to the layer surface on the back coat layer side, it imparts remarkable lubricity to the layer surface, improving runnability and durability. has been significantly improved,
In addition, corrosion resistance is significantly increased.

The total amount applied to the surface layer is 05 to 30 mg/m", preferably 1 to 10 m9/71:. When used as an overcoat layer such as a lubricating layer or antirust layer on the surface layer, the film thickness is 50 to 30 mg/m". 500λ is preferable.If it is 5001A or more, the spacing loss will be large, and if it is thinner than 50A, the lubricity will be poor.
The effect on corrosion resistance will be reduced. 5. Use of other lubricants, such as fatty acid esters, in combination with the above compounds gives even better results for the lubricity. Lubricants that can be used in combination include silicone oil, graphite, carbon black graft polymer, molybdenum disulfide,
Examples include fatty acids such as tungsten disulfide, lauric acid, balmitic acid, oleic acid, stearic acid, behenic acid, and myristic acid, and fatty acid esters such as butyl stearate, octyl palmitate, and octyl myritate.

A layer surface containing a mixture of these compounds is formed by applying a paint, which paint contains a mixture of said compounds at 0%.
．． 005 Consists of an organic solvent solution containing from 1% to 1% by weight. Organic solvents for this purpose include toluene, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, xylene, benzene, cyclohexanone, methanol, ethanol, propatool, isopropanol, butanol, ethyl cellosolve, methyl cellosolve, etc. alone or in combination. used.

To apply this paint, there is a dipping method where the paint is immersed in the paint, a reverse roll method where the paint is applied,
An extrusion method, a doctor blade method, a gravure printing method, a spray method, etc. are used, and the coating film applied by these methods is dried by ordinary means.

The ferromagnetic metal thin film in the present invention includes Fe, Co,
Metals such as Ni or Fe-Co% Fe-Ni%
Co-Ni% Fe-Co-Ni, Fe-Rh
%Fe-Cu %Co-Cu %Co-Au
XCo-Y, Co-La, Co-Pr,
Co-(3d, co-3m.

Co-Pt, Ni-Cu, Mn-B1, M
n-8b, Mn-Al, Fe-Cr+, C
o-Cr, Ni-Cr, Pe-Co-Cr%
A ferromagnetic alloy such as Fe-Co-Nl-Cr formed into a thin film by vacuum deposition is used. The thickness of this metal thin film is preferably about 500A to 5000A.

Furthermore, those deposited in an oxygen atmosphere exhibit better durability.

Regarding the coated magnetic layer and back coat layer, conventional techniques can be used as they are.

The support on which the metal thin film is formed may be a plastic base such as polyester, polyethylene terephthalate, polyimide, polyamide, polyamide, polyvinyl chloride, cellulose triacetate, polycarbonate, polyethylene naphthalate, or AISA1 alloy, TI% 'p+ An alloy, a metal plate such as stainless steel, etc. are used.

〔Example〕

Next, the present invention will be explained in detail, but the present invention is not limited thereto.

Example 1 Co-layer on polyethylene terephthalate with a thickness of 12 μm
Ni (Ni 20 weight IX%) thickness 100
A thin metal film layer was formed by depositing 0.0×2. A lubricant as shown below was dissolved in a toluene-ethyl cellosolve mixed solvent (9:1) and applied onto this metal thin film layer. Then, they were dried, slit, and packed into cassettes to give samples 1 to 11.

Trial r11 (Comparative sample) Cobalt stearate 5m9/d Sample 2 (
Comparative sample) (C+aT-T3sO)3PO51Hg/d Sample 3 (
Comparative sample) (C+□H2sO)3 Po 5
m97 m” sample 4 (comparative sample) Cobalt laurate 5 m9/rn” sample 5
(hereinafter the sample of the present invention) cobal stearate) 5m9/m” (C
I6H330)3 PO5my/lr? Sample 6 Cobalt stearate 2m9/m (CI6
H1130)3 Po 4■/d Sample 7 Cobalt stearate 5m9/rrl (C+
2I-12aO)sPo
5 m977B” Sample 8 Cobalt laurate 5 m9/i (C+a
HssO)3P0 5 mg/m" Sample 9 Cobalt laurate 2 m97 m" (
C+aHssO)3P0 5 m9/
m” Sample 10 Cobalt laurate 5m9/go(C, 2H
250) 3PO5m9/rrt Sample 11 Cobalt Laurate 2 m97 m” (
CI21-T250) 3 Po 5
m9/m" The coefficient of friction of the magnetic surface of the magnetic tapes of Samples 1 to 11 was measured, and the cassettes were placed on a deck to observe running performance, still durability, and repeated playback durability. The results are shown in Table 1. Shown below.

From Table 1, it can be seen that when the two types of lubricants of the present invention are used together, the coefficient of friction is smaller, the running performance is improved, and the still durability and repeated durability are significantly improved compared to when they are used alone. Ru.

Table 1

Claims (1)

[Claims] A magnetic recording medium comprising a combination of a fatty acid soap and a phosphoric acid ester on the layer surface of the magnetic recording medium.