JPS6295721A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a thin metallic film type magnetic recording medium having excellent runnability, wear resistance, a wheatherability and electromagnetic conversion characteristic by providing a layer contg. a compd. having a specific group on the surface of a thin ferromagnetic metallic film provided on a nonmagnetic base. CONSTITUTION:The layer contg. the compd. expressed by the formula I is provided on the surface of the thin ferromagnetic metallic film provided on the non-magnetic base. An alkyl succinic anhydride, alkenyl succinic anhydride, various maleated oils, and ester of maleated oils and a aliphat. alcohol are particularly preferable as the above-mentioned compd. and the alkyl group of these compds. is more preferably 8-30C. A lubricating agent may be mixed with or laminated on the protective film provided on the surface of the thin magnetic metallic film. The thickness of the protective layer is 0.5-100mg/m<2>, more preferably 2-20mg/m<2>. The surface of the thin metallic film may be reformed by a surface active agent such as fatty acid prior to the provision of the protective film in order to improve the adhesion to the thin underlying metal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium comprising a ferromagnetic metal thin film as a magnetic recording layer, and particularly to a metal thin film type magnetic recording medium having excellent running properties and wear resistance. It is something.

[Prior art]

Conventionally, as a magnetic recording medium, r-
Fe203, CO doped r Fe2O3+Fe
304=Co-doped r Fe2O3+Fe3O
A magnetic material such as the bertolide compound of 4, magnetic powder such as CrO2, or ferromagnetic metal powder is dispersed in an organic binder such as vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer, epoxy resin, polyurethane resin, etc. Paint-on type products, in which a substance is applied and dried, have been widely used.

In recent years, with the increasing demand for high-density recording, ferromagnetic metal thin films formed by single-layer T-deposition methods such as vacuum evaporation, sputtering, and ion blating, or plating methods such as electroplating and electroless plating. A so-called metal thin film magnetic recording medium, which does not use a binder and has a magnetic recording layer of BACKGROUND ART as a magnetic recording layer, is attracting attention, and various efforts are being made to put it into practical use.

As one of the conditions required for magnetic recording media for high-density recording, high coercive force and thinness have been proposed both theoretically and experimentally. There are great expectations for metal thin film magnetic recording media, which can be easily made small and thin and have a high saturation magnetic flux density.

In particular, the method using vacuum evaporation has great advantages because it does not require waste liquid treatment as in the case of plating, the manufacturing process is simple, and the deposition rate of the film can be increased. A method for manufacturing a magnetic film having coercive force and squareness desirable for magnetic recording media by vacuum deposition is disclosed in U.S. Pat. No. 33≠2632.
The oblique vapor deposition method described in No. 33≠2t33 is known. Furthermore, major problems associated with magnetic recording media made of ferromagnetic metal thin films include poor weather resistance, runnability, and abrasion resistance. In the process of recording, reproducing, and erasing magnetic signals, the magnetic recording medium is subjected to high-speed relative motion with the magnetic head, but in this case, the movement must be smooth and stable, and at the same time, contact with the head and No wear or breakage shall occur. Furthermore, it must not corrode and maintain stable running performance and magnetic properties even when stored in harsh environments such as high temperature and high humidity conditions. Against this background, consideration has been given to providing a lubricating layer or a protective layer as a method of improving running performance, durability, and weather resistance.

The protective layer of a metal thin film type magnetic recording medium may be formed by dissolving a thermoplastic resin, a thermosetting resin, a fatty acid, a metal salt of a fatty acid, a fatty acid ester, an alkyl phosphate ester, or the like in an organic solvent.

(For example, JP-A-1217, JP-A-6
(Refer to Publication No. 27) [Problems to be Solved by the Invention] However, the runnability, abrasion resistance, and weather resistance of the metal thin film magnetic recording medium thus obtained are insufficient, and the provided protection is insufficient. Due to the thickness of the layer, there are problems such as deterioration of electromagnetic conversion characteristics due to sinking loss due to the spacing between the head and the tape.
Improvements are still desired for the practical application of metal thin film magnetic recording media.

An object of the present invention is to provide a metal thin film magnetic recording medium that has excellent running properties, wear resistance, weather resistance, and electromagnetic conversion characteristics.

[Means to solve the problem]

As a result of intensive studies on metal thin film type magnetic recording media, the present inventors found that a divalent metal film represented by the following formula (I) was formed on the surface of a ferromagnetic metal thin film provided as a magnetic recording layer on a non-extractive support. In a magnetic recording medium formed by forming a layer containing a compound having a group, the wear resistance against components such as a magnetic head and guide balls is significantly improved, and the coefficient of friction against traveling system components is reduced, resulting in even better performance. It was discovered that the material also has weather resistance, leading to the present invention. That is, the above-mentioned object of the present invention is to apply the following to the surface of a ferromagnetic metal thin film formed on a support by a method such as electroplating, electroless plating, vapor phase plating, snog splattering, vapor deposition, or ion blating. This is achieved by a magnetic recording medium provided with a layer containing a compound having a divalent group shown in the formula in its molecule.

Compounds used in the present invention include organic compounds and organometallic compounds having a divalent group represented by the above formula in the molecule. Further, the number of groups represented by the above formula contained in the molecule may be one or two or more.

Examples of compounds containing the group represented by the above formula include n-octadecylsuccinic anhydride, in-octadecylsuccinic anhydride, octylsuccinic anhydride, n)"f silsuccinic acid 1/f, hydrate, n-dodecenylsuccinic anhydride, Acid anhydride, substituted or unsubstituted /, 2,3,1°-tetrahydrophthalic anhydride, various maleated oils (also called maleic oxidized oils: synthesized by reacting unsaturated fatty acids with maleic anhydride) Examples include esters of maleated oil and aliphatic alcohol, amides of maleated oil and aliphatic amine, and various other compounds produced by addition reactions of maleic acid.Among these, particularly preferred are alkyl succinates. Acid anhydrides, alkenylcono-phosphate anhydrides, various maleated oils, esters of maleated oils and aliphatic alcohols, and more preferably alkyl succinic anhydrides in which the alkyl group has at least 30 carbon atoms. , alkenylsuccinic anhydride, various maleated oils, and esters of maleated oil and aliphatic alcohol.In the case of alkylsuccinic anhydride or alkenylsuccinic anhydride, when the number of carbon atoms in the alkyl group is less than 1. However, it is not preferable to use them alone because the running properties of the magnetic recording medium may be deteriorated.

However, as described below, this does not apply when used in a mixed system with other lubricants. There are compounds with high molecular weights that contain divalent groups represented by the above formula, but in this case, it is difficult to form a thin film with a uniform thickness (adhesion amount), and as a result, compounds with low molecular weights are difficult to form. It is not preferable because the properties, especially the weather resistance, are inferior.

In the present invention, the protective layer provided on the surface of the mother metal thin film may contain one or more compounds containing a divalent group represented by the above formula (I) and a general lubricant mixed or laminated therein. . Lamination refers to providing a general lubricant layer on top of a layer containing seven or more types of compounds containing groups represented by the above formula. If the compound containing the divalent group represented by the above formula alone has insufficient running properties, this mixed use,
Lamination is a very effective means.

Examples of lubricants that can be mixed with a compound containing a divalent group represented by the above formula include fatty acids, metal soaps, fatty acid amides, higher aliphatic alcohols, aliphatic alcohols and fatty acids, phosphoric acid, phosphoric acid, titanic acid, silicic acid, etc. Esters with various acids, fluorine substituted products of the above, paraffins, silicone oils, animal and vegetable oils, mineral oils, higher aliphatic amines; Inorganic fine powders such as graphite, silica, molybdenum disulfide, tungsten disulfide, etc.: polyethylene, polypropylene , fine resin powders such as polyvinyl chloride, ethylene-vinyl chloride copolymer, and polytetrafluoroethylene; α-olefin polymers: unsaturated aliphatic hydrocarbons and fluorocarbons that are liquid at room temperature. Among these, particularly preferred are fatty acids, metal salts of fatty acids (metal soaps), fatty acid amides, esters of aliphatic alcohols with various acids such as fatty acids, phosphoric acid, phosphoric acid, titanic acid, and silicic acid, and fluorine substitution thereof. Things, etc.

In the present invention, the method for forming the surface protective layer is as follows:
A method in which the material is dissolved in an organic solvent, applied or sprayed onto the substrate, and then dried; a method in which the material is melted and applied to the substrate; a method in which the material is applied to the substrate surface by immersing the substrate in a solution in which the material is dissolved in an organic solvent. Examples include a method of adsorption, and a method of forming a monomolecular film of the material on the substrate surface using the Langmuir-Prodgett method.

The thickness of the protective layer provided in the present invention (the amount present will be referred to as thickness here) is O0! M9/m2~
ioomgt777&2 is preferred, more preferably 2
Hit/rn24~λO■/m2. Thickness is 0.
! If it is less than rny/m2, it is difficult to form a uniform film, and the runnability and durability are insufficient.

Further, if the thickness is 100 y/m2 or more, there is a problem that electromagnetic conversion characteristics deteriorate due to spacing loss between the head and the tape.

In addition, in the present invention, in order to improve the adhesion of the protective layer to the base metal thin film, the surface of the base metal thin film is coated with a surfactant such as a fatty acid, various chelating agents, and various coupling agents before applying the protective/lubricant agent. It can also be modified.

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

Materials for the ferromagnetic metal thin film include iron, cobalt, nickel, and other ferromagnetic metals, or FeCo+Fe-N+ +
CONi + Fe Rh + Co P + Co
B+Co Y+Co La, Co Ce+Co
-Pt + Co-3m, CoMn + p
e-co-Ni +Co Ni Pico Ni
B, Co Ni-Ag+Co-N1-Nd
+ Co-N 1-Ce + Co-N i -Zn
.

Co-Ni-CusCo-Ni-VLCo
-N 1-Re and other ferromagnetic alloys are formed by electroplating, electroless plating, vapor phase plating, snow plating, vapor deposition, ion blating, etc., and the film thickness is suitable for use as a magnetic recording medium. If you do, 0,0 1 µ
m range, and especially the range of Q, O, 10, ≠μ doors is desirable.

The above ferromagnetic metal thin film also has 0 + N + Cr +
G a +ASISrlZrlNb1MOIRhlP
clSnlSb+Te+Pm+Re+Os+Ir+Au
+HgtPb, Bi, etc. may be included.

The surface shape of the above magnetic layer is not particularly defined, but 1o-
Existence density of protrusions with height of iooo^ is ios~io9/m
If you have 2, even more! Particularly when it has protrusions with a height of 0-200^ with a density of 104-108/2, it has excellent runnability and durability.

The thickness of the support is preferably Hiroshi~jQ,urn. Further, an underlayer may be provided on the support in order to improve the adhesion and magnetic properties of the ferromagnetic thin film.

The substrate used in the present invention is a plastic base such as polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride, cellulose triacetate, polycarbonate, polyethylene naphthalate, polyphenylene sulfide, or AI.

Ti + stainless steel can be used.

The magnetic recording medium may have any shape such as tape, sheet, card, or disk, but tape and disk shapes are particularly preferred.

〔Example〕

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

Example 7 A cobalt-nickel magnetic film (film thickness 1!Onm) was obliquely deposited on a 3 μm thick polyethylene terephthalate film to prepare a raw material for a magnetic recording medium. An electron beam evaporation source was used as the evaporation source, and it was charged with cobalt-nickel alloy (Co:♂Owt%, Ni:CoO), and the incident angle was set at 50°C in a vacuum of JX/0” Torr.
Oblique evaporation was performed to obtain the desired temperature. Various materials dissolved in methyl ethyl ketone were coated on the magnetic metal thin film of the obtained magnetic recording medium, and samples were prepared by drying and designated as samples A/-t (Table 1). of the obtained magnetic tape (
A) λz 0cXrots relative humidity 1 [[(B) 2j 0
C. The friction coefficient, ie, μ value, against a stainless steel rod at 10% relative humidity, repeated running durability on a t-millimeter VTR, still durability, and weather resistance were investigated, and the results are shown in Table 2.

What is repeated running durability? Transfer Om length tape to r mm type VTR (Fuji Photo Film ■: FUJIX-F M
This is the number of times the screen is repeatedly played until the screen becomes distorted due to unstable running or the running stops due to an increase in the coefficient of friction. Still durability was evaluated by pressing the pause button during image playback using a VTR of the same type (however, the function to limit still playback time was removed) and measuring the time until the image stopped appearing. In addition, the weather resistance is 60°
Evaluation was made based on the changes that occurred on the surface when stored for 70 days under the conditions of C1 relative humidity Hqo%.

(Things with no change at all...○, Spots of discoloration areas observed on the surface under a 100x microscope...Δ, Things with obvious discoloration or corrosion when observed with the naked eye...
In this way, the metal thin film magnetic recording layer provided on the surface with a layer containing a compound having a divalent group represented by the above formula (I) is excellent in μ value and repeatability, and has excellent It is clear that the characteristics are realized under a wide range of conditions from high humidity to low humidity.

〔Effect of the invention〕

The magnetic recording medium of the present invention is a metal thin film type magnetic recording medium that has excellent runnability, durability, and weather resistance that could not be achieved using conventional techniques.

Claims (1)

[Claims] (1) A magnetic recording medium characterized in that a layer containing a compound having a group represented by the following formula is provided on the surface of a ferromagnetic metal thin film provided on a nonmagnetic support. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼