JPS6383910A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a thin metallic film type magnetic recording medium having excellent still durability and output stability by providing a thin ferromagnetic metallic film or thin alloy film and protective lubricating layer contg. a compd. having a mercapto group on one face of a base and providing a back layer contg. a carbon black on the other face. CONSTITUTION:The back layer contg. the carbon black is provided on the other face of the magnetic recording medium formed by forming the thin ferromagnetic metallic film one one face of the nonmagnetic base and providing the protective lubricating layer contg. the compd. having the mercapto group thereon. The particle size of the carbon black to be incorporated therein is in a 50-500mmu range and the average particle size thereof is preferably >=150mX. The carbon black is bonded by a binder and the amt. of the carbon black to be used to 10-100wt% by the weight of the binder. The thikness of the protective lubricating layer is preferably 0.5-100mg/m<2>, more preferably 2-20mg/m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and particularly to a metal thin film type magnetic recording medium that has excellent still durability and output stability.

[Conventional technology]

Conventionally, as magnetic recording media for audio, video, or computers, so-called "coating-type" magnetic recording media, in which iron oxide magnetic powder is dispersed in various binders and coated on a non-magnetic support, have been commonly used. It was a target.

On the other hand, requirements for magnetic recording media have become stricter, such as decreasing the recording wavelength and narrowing the track width in order to increase the recording density. Development of "thin-film type" magnetic recording media is currently underway, and some of them have been put into practical use.

Various studies have been conducted to improve the characteristics of this metal thin film type magnetic recording medium, and one of them is that there is almost no rust on the surface of the magnetic layer even under high temperature and high humidity conditions, and that the magnetic characteristics change over time. In order to reduce the amount of rust, it has been proposed to attach a rust preventive agent whose main component is a compound having a mercapto group to a ferromagnetic metal thin film (Japanese Patent Application Laid-Open No. 82324/1983).

In addition, in order to avoid an increase in the coefficient of friction, improve running durability, and provide excellent curl resistance, carmen black is bonded to the surface of the magnetic recording medium opposite to the surface having the magnetic recording layer. It has also been proposed to provide a back layer containing an agent (
(Japanese Unexamined Patent Publication No. 59-218632), this method was applicable to both general coated tapes and metal thin film magnetic tapes.

For metal thin film type magnetic recording media, is it a metal thin film or an alloy thin film on a non-magnetic support? Although it is directly formed using techniques such as vacuum evaporation, sputtering, ion blating, and plating, it is different from coating-type recording media because it does not undergo a calendaring process after coating. The running durability was poor.

[Problem that the invention seeks to solve]

The present invention has been made under the above circumstances, and its object is to provide a metal thin film type magnetic recording medium that has excellent still durability and output stability.

[Structure of the invention]

In the present invention, a ferromagnetic metal thin film or alloy thin film (hereinafter both thin films are simply referred to as "metal thin film") and a protective lubricating layer containing a compound having a mercapto group are provided on one side of a nonmagnetic support, and the other side The magnetic recording medium is characterized in that a back layer containing carzen black is provided on the magnetic recording medium.

Non-magnetic flexible supports used in the present invention include cellulose acetate: cellulose nitrate: ethyl cellulose: methyl cellulose; polyamide; polymethyl methacrylate: polytetrafluoroethylene y: yN li)! J
Fluoroethylene; alpha like ethylene, fluoropylene
Polymer or copolymer of vinyl chloride; Polyvinylidene chloride; Polycarbonate; Polyimide: Polyesters such as polyethylene terephthalate are used, but from polyethylene terephthalate, polyamide, polyimide, etc. Plastic supports are suitable.

The material of the ferromagnetic metal thin film provided on the support may be iron, cobalt, nickel or other ferromagnetic metals, or IPs-Co, lPe-Ni, Co-Ni.
, Fe-Rh, co-P, Co-B, Co-
Y, Co-La, Co-0e.

Co-Pt, Co-am, Co-Mn, 0
o-Cr, Fe-Go-Ml.

Co-Ni-? , Co-N1-B, C! o-N
i-mug, co-11-Nd.

Co-Ni-Ce, Go-Ni-Zn, Co-
N1-(!u, Co-111-W.

A ferromagnetic alloy such as Co-Ni-Be is formed by electroplating, electroless plating, vapor phase plating, sputtering, vapor deposition, ion blating, etc., and the film thickness is the same as when used as a magnetic recording medium. (LO2-2
It is preferably in the range of μm, particularly preferably in the range of (LO5−(L4 μm).

The above-mentioned ferromagnetic metal thin films include KO, N, Or, and Ga.

As, Br, Zr, Nb, Mo, Rh, P
d, an, 8'b.

To, Fm, Re, Ota, 工r, mu, Hg
, Pb, Bi, etc.

Furthermore, it is optional to provide a base layer or an undercoat layer, or to form multiple metal thin film layers, if necessary.

After forming the ferromagnetic metal thin film as described above, a protective lubricant layer containing a compound having a mercapto group is provided thereon.

The compound having a mercapto group used in the present invention is generally a mercapto compound having a saturated or unsaturated substituted or unsubstituted hydrocarbon group, and may have a cyclic structure. Organic compounds with relatively high molecular weight and low volatility give good results. A particularly preferred one is R"-X-X-R" (Kl and B2 are substituted or unsubstituted hydrocarbon groups, and at least one of Bl and B2 is a hydrocarbon group substituted with a mercapto group. 00-,-80,-,-080,-,-PO(
OII)-.

-PO (OR Lee: Y is -11H-, -HR4-,
-0-: HR is a substituted or unsubstituted hydrocarbon group; R4 is a substituted or unsubstituted hydrocarbon group) An ester or amide compound or a mercapto compound having a heptafluorinated alkyl group is preferable.

Among these, preferred are behenyl β-mercaptopropionate, octadecyl β-mercaptopropionate, dodecyl β-mercaptopropionate, and β-mercaptopropionate.
Octyl mercaptopropionate, oleyl β-mercaptopropionate, behenyl thioglycolate, octadecyl thioglycolate, dodecyl thioglycolate,
Octyl thioglycolate, oleyl thioglycolate, behenyl thiosalicylate, octadecyl thiosalicylate, dodecyl thiosalicylate, octyl thiosalicylate, methyl thiosalicylate, oleyl thiosalicylate, 2-mercaptoethyl stearate, 2-mercaptoethyl ophinate, 2-mercaptoethyl myristate and 2-mercaptoethyl laurate, more preferably behenyl β-mercaptopropionate, octadecyl β-mercaptopropionate, dodecyl β-mercaptopropionate, oleyl β-mercaptopropionate, and thioglycolic acid. Behenyl, octadecyl thioglycolate, dodecyl thioglycolate, oleyl thioglycolate, 2-mercaptoethyl stearate, 2-mercaptoethyl oleate, 2-mercaptoethyl myristate, octadecyl thioglycolate, octadecyl β-mercaptopropanesulfonate ,'4 FIT
〇-φ-C, H481! (φ is a phenylene group),
Al in etc.

In the present invention, the protective lubricant layer provided on the surface of the ferromagnetic metal thin film may contain one or more of the mercapto group-containing compounds listed above as well as a general lubricant.

In addition to compounds having a mercapto group, lubricants that can be mixed include fatty acids, metal soaps, fatty acid amides, fatty acid esters, higher aliphatic alcohols, monoalkyl phosphates, dialkyl phosphates, trialkyl 7-mole 7-ate, paraffins, Silicone oil, animal and vegetable oil, mineral oil, higher aliphatic amine: graphite, silica,
Inorganic fine powders such as molybdenum disulfide and tungsten disulfide; fine resin powders such as polyethylene, polypropylene, polyvinyl chloride, ethylene-vinyl chloride copolymers, polytetrafluoroethylene, etc.; a.Olefin polymers; unsaturated liquid at room temperature Examples include aliphatic hydrocarbons and fluorocarbons.

In the present invention, the surface protective lubricant layer can be formed by dissolving the material in an organic solvent, applying or spraying the material to the substrate, and then drying it, melting the material and applying it to the substrate, or using an organic solvent. Examples include a method in which the substrate is immersed in a solution in which the material is dissolved to cause the material to be adsorbed onto the substrate surface, and a method in which a monomolecular film of the material is formed on the substrate surface by the Langmier-Air-Project method.

The thickness of the protective lubricant layer provided in the present invention (the amount present will be referred to as thickness here) is -1lL5111
/-~100 MI/- is preferable, preferably 2)
at/- to 20 ay/-. Thickness is 15q/m"
If it is less than that, it is difficult to form a uniform film, and the runnability and durability are insufficient. Also, the thickness is 10011P/p
If it is more than H'', the electromagnetic conversion characteristics will deteriorate due to spacing loss between the head and the tape.

Furthermore, in the present invention, in order to improve the adhesion of the protective lubricant layer to the base metal thin film, the surface of the base metal thin film is modified with a surfactant such as a fatty acid or various coupling agents before forming the protective lubricant layer. You can also do that.

Further, the protective lubricant layer may be one layer or may consist of a plurality of layers.

As described above, a ferromagnetic metal thin film is formed on one side of a nonmagnetic support, and a layer containing a compound having a mercapto group is provided thereon.A back layer containing carbon black is provided on the other side of the magnetic recording medium. .

Particle size of carbon black to be included: aso ~ 500 mμ
It is preferable that the average particle size is 15 (la μ or more). Carbon black is bonded with a binder, and the amount of carbon black used is 10 to 100 wt% based on the binder. A specific example of the carbon black used is R manufactured by Columbia Carbon Co.
aven MT-P (280 mμ) is suitable.

As the binder for the back layer, there may be used binders conventionally known in the art, such as thermoplastic resins, thermosetting resins, reactive resins, or mixtures thereof. For example, the binders shown below can be selected, but the glass transition temperature Tg of one type or a mixture of two or more types is 4.
It is desirable that it melts at 0C or higher, and particularly preferably that 'rg is 60C or higher.

Examples of thermoplastic resins include vinyl chloride-vinylacetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, and acrylic ester-vinylidene chloride copolymer. , acrylic ester-styrene copolymer 1 methacrylic ester-acrylonitrile copolymer, methacrylic ester-vinylidene chloride copolymer,
Methacrylic acid ester-styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose resin (cellulose acetate butyrate, cellulose dye) acetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymers, polyester resins, chlorovinyl ether-acrylic acid ester copolymers, amino resins, and various rubber resins.

Examples of thermosetting resins or reactive resins include phenolic resins, epoxy resins, poly9 urethane curable resins, urea resins,
Melamine resin, Alyado resin, Acrylic reaction resin,
These include polyisocyanates and polyamines.

The thickness of the back layer of the present invention is preferably 11 to 3 microns, particularly preferably 13 to 2 microns.

〔Example〕

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example 1 A cobalt-nickel magnetic film (1Ai: 20 atoms) t-thickness 200 nm was deposited on a 115 μm thick polyethylene terephthalate film 2 using a roll-up vapor deposition apparatus (FIG. 1) having a cylindrical can 1. Deposit diagonally so that
A raw material for a magnetic recording medium was created. 50 as an evaporation source
Using a KW electron beam evaporation source 5, a gas introduction boat 6.
7 to 01 The film was deposited at a rate of 60 m/min with a film feed bead while flowing the gas at 16000 C/min. The minimum incident angle θ of the vapor flow with respect to the normal to the film surface was 55 degrees. 3
4 is an incident angle regulating mask, and 4 is a crucible and a vapor deposition material.

Various materials shown in Table 1 were dissolved in methyl ethyl ketone on the surface of this raw film on which the magnetic metal thin film was provided.
all/- coated and dried. On the opposite side, a back layer t-0, having a thickness of 61NIn, was provided as shown in Table 2.

These original films were slit into 8-width strips to obtain tape-shaped samples.

The still durability, jitter, and output stability of the resulting nine magnetic tapes were investigated and the results are shown in Table 3.

Here, the still durability is 23 and 70 RIi.

230101R]! Measured the time until the output deteriorates by 3 dB during still playback with an 8mm VTR (Fuji Photo Film: πJ-X-8M 6 type) [however, the mechanism that limits still playback time is removed] under the following environment. evaluated.

The stability of jitter and output was determined by recording the tape at 23°C under 7091RII for 60 minutes and placing the tape in an atmosphere of 70% RE and 80% RE at 50°C: 1
After storage for a week, the sample was brought into an atmosphere of 2311:10% RH and regenerated, and the measurements were taken. The jitter was determined as the average value of the values measured using a jitter meter (MK-6111 manufactured by Meguro Electronics). The stability of the output was evaluated based on the fluctuation range of the reproduced output.

Table 1 Types of surface lubricants Table 2 Types of back layers [Effects of the invention] According to the present invention, the still durability of the magnetic recording medium is improved,
In particular, jitter during storage under high temperature and high humidity conditions is reduced, output fluctuations are also significantly reduced, and products with improved properties are obtained.

In the above-mentioned conventional technology in which a compound having a mercapto group is attached to a ferromagnetic metal thin film, the compound is used as a rust preventive agent, but in the present invention, this compound actually has a lubricating effect. It is something that is discovered and used in that sense.

In addition, in other conventional techniques in which a back layer containing carbon black is provided on a magnetic recording medium, it is said that by providing the back layer, the friction coefficient can be lowered, running durability is improved, and curl resistance is improved. However, in the present invention, by using both the lubricating layer and the backing layer, the jitter value is considerably reduced and the output fluctuation is significantly reduced, which cannot be achieved individually, but is based on the combination of both. Remarkable effects can be obtained. %, as seen in the implementation column 1, T, which is a combination of both, +1- J v L-B
In the desired case, the jitter value is small and the output fluctuation is as small as 0.

[Brief explanation of the drawing]

FIG. 1 shows that when manufacturing 1 ka of the magnetic recording medium of the present invention,
This figure shows a device a used in the process of providing a metal thin film on a nonmagnetic support.

Claims (1)

[Claims] 1) A ferromagnetic metal thin film or alloy thin film and a protective lubricating layer containing a compound having a mercapto group are provided on one side of the nonmagnetic support, and a back layer containing carbon black is provided on the other side. A magnetic recording medium characterized by: