JPH043328A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To uniformly form a lubricating film on a magnetic recording layer and to improve lubricity and durability by providing a lubricating layer contg. specific org. compds. CONSTITUTION:If the lubricating layer contg. >=1 kinds of the org. compds. expressed by formulas I to IV are provided on the recording layer, the org. compds. have a perfluoroalkyl group, aliphat. hydrocarbon and polar high level in one molecule and, therefore, the compds. have the good compatibility with the material on the surface of the magnetic recording layer and the lubricating film is formed uniformly on the magnetic recording layer, by which the magnetic recording medium having the enhanced lubricity and durability is obtd. In the formulas, n: 0 to 3 integer, R: >=8C substd. or unsubstd. aliphat. hydrocarbon, RF: >=4C perfluoroalkyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application in M Industry] The present invention relates to a magnetic recording medium. More particularly, the present invention relates to magnetic recording media having improved lubricating layers.

[Prior Art] Magnetic recording technology is used in a wide range of fields as a rewritable recording method. As can be seen from the recording principle of this method, in order to perform effective recording and reproduction, the magnetic head
It is necessary to reduce the distance between recording media as much as possible.

As a result, collisions and sliding occur frequently between the magnetic head and the recording medium, and therefore frictional wear between the magnetic head and the recording medium becomes an extremely serious problem. In particular, recently, with the increasing demand for high-density recording, it has become necessary to narrow the spacing between the magnetic head and the recording medium and to develop thin film type recording media that are considered to be radiationally susceptible to frictional wear. In particular, thin-film recording media have metal exposed on the surface of the magnetic recording layer, which is easily scraped by the sliding of the head, and requires high lubricity.

Therefore, the key point for practical application is how well the friction and wear problem mentioned above can be solved.

Furthermore, although the durability of the coated magnetic recording media that is currently in practical use is not a problem in practical use,
Achieving higher reliability in terms of durability is extremely important from the perspective of reducing the incidence of accidental product failure.

[Problems to be Solved by the Invention] In order to improve this point, it has been proposed to apply various lubricants to the surface of the magnetic recording layer.

However, for example, perfluoroalkyl polyether tends to cause sticking, and fatty acid-based lubricants have drawbacks such as accelerating corrosion of the magnetic layer. Not yet reached.

The present invention aims to solve the drawbacks of the conventional products described above, such as poor running characteristics or poor corrosion resistance, and thereby provide a magnetic recording medium with excellent durability.

[Means for Solving the Problem] As a means for achieving the above object, the present invention provides a magnetic recording medium comprising a non-magnetic substrate and a magnetic recording layer.
A magnetic recording medium is provided, characterized in that a lubricating layer containing at least one organic compound selected from the group consisting of the following formulas (I) to (TV>) is provided on a magnetic recording layer.

(In the formula, n is an integer of O to 3, R is a substituted or unsubstituted aliphatic hydrocarbon group having 8 or more carbon atoms, and RF is a perfluoroalkyl group having 4 or more carbon atoms. ) R is, for example, an alkyl group having 8 or more carbon atoms (preferably linear) or an alkylene group having 1 to 4 double bonds, and some or all of the hydrogens in R are substituted with fluorine. You can.

[Function] The organic compound used in the present invention has a perfluoroalkyl group, an aliphatic hydrocarbon group, and a polar moiety in one molecule, so that the metal, metal oxide, binder, rust preventive material, etc. on the surface of the magnetic recording layer are It is compatible with all substances, including other lubricants, and can form a uniform lubricant film on the magnetic recording layer, resulting in high lubricity and durability.

Furthermore, the organic compound used in the present invention can be mixed with magnetic paint, back coat paint, anticorrosion paint, other lubricant paint, etc. and applied.

Further, the compound of formula (I) is a substance obtained by subjecting an alkyl isocyanate and a fluoroalkyl alcohol to a M addition reaction, and the compound of formula (II) is a substance obtained by subjecting an alkyl isocyanate to a polyaddition reaction of a fluoroalkyl amine, and the compound of formula ( The compound of formula 1') is a substance obtained by polyaddition reaction of an alkyl isothiocyanate and a fluoroalkyl alcohol, and the compound of formula 1') is a substance obtained by a polyaddition reaction of an alkyl isothiocyanate and a fluoroalkyl amine. All of them are highly stable and hard to change in quality, so they do not attack the magnetic recording layer, and their lubricating properties do not change much even after long-term storage or being left in a corrosive environment.

In the organic compound having the above structure used in the present invention, in order to exhibit sufficient lubricity, the number of carbon atoms in R must be 8 or more, and the number of carbon atoms in RF must be 4 or more. is preferably linear.

Further, when this organic compound is a liquid, it is preferable to have a double bond in R in order to lower the viscosity and prevent stick-slip or adhesion with the head. If the number of double bonds is too large, the degree of freedom of the alkyl chain will be reduced and the lubricity will be lowered, so the number of double bonds is preferably 4 or less.

As a method for forming the above-mentioned lubricating layer on the magnetic recording layer, all conventional organic layer forming methods such as gravure coating, spin coating, and vacuum evaporation are preferably used. In addition to the method of directly forming the lubricant on the magnetic recording layer, various methods can be adopted, such as forming a lubricant layer on the back surface and transferring it to the magnetic recording layer, or incorporating it into a magnetic paint or back coat paint.

The magnetic recording layer formed on the substrate is, for example, γ-Fe2
03 powder, Fe3O4 powder, Co-impregnated r-Fe203 powder, Co-containing Fe3O4 powder, Fe powder, Co powder, F
A coated type formed by applying magnetic powder such as e-Ni powder together with a binder component, an organic solvent, etc. onto a substrate and drying it, or a C0% Fe1Ni1Co-Ni alloy, C0-Cr alloy, Co-P alloy , Co-N1-P alloy, or other thin film type formed by depositing a ferromagnetic metal or alloy on a substrate by means such as vacuum evaporation, ion blasting, sputtering, or plating. However, particularly excellent effects of the present invention are exhibited in thin-film magnetic recording media.

When the magnetic material is Co alone or a Co alloy, it is also possible to oxidize it to form a Co passive layer on the surface. In this case, a lubricating layer is formed on the surface of the Co passive layer.

Magnetic recording media include magnetic tapes based on synthetic resin films such as polyester films and polyimide films, and magnetic disks and magnetic drums based on glass plates, aluminum plates, synthetic resin plates, etc., which have a structure that makes sliding contact with the magnetic head. It includes various forms.

[Example code] The present invention will be explained in more detail below using Example F1.

Actual 111F: A polyester film with a thickness of 10 μm was set in a vacuum evaporation device and heated to a vacuum temperature of 10 −6 Torr.

The 8ONi20 alloy was heated and evaporated to form a CoNi ferromagnetic metal thin film layer with a thickness of 2000 nm on the polyester film. Thereafter, the sample was left in an oxygen atmosphere of 3 atm for 50 hours to form a Co passive film with a thickness of 50 mm on the ferromagnetic metal thin film magnetic layer. Next, the polyester film on which the ferromagnetic metal thin film layer was formed was set in a gravure coating device, and 0.1 wt% ZS90 (manufactured by Montegisson) of an organic compound with the following structure was applied as a lubricating paint to the surface on which the ferromagnetic metal thin film layer was formed. The solution was applied and dried to form a 150 mm thick lubricating layer on the ferromagnetic metal thin film layer. The tape was then cut to a specified width to make magnetic tape.

A magnetic tape was prepared in the same manner as in Example 1, except that a 0.1 wt % ZS90 solution of an organic compound having the following structure was used as the lubricating paint.

As the lubricating paint in Example 1, Q, 1wt% ZS, which was a mixture of the organic compound used in Example 1 and Fomblin Z-AM20Of (manufactured by Montegisson) at a weight ratio of 1:1, was used.
A magnetic tape was made in the same manner except that 90 mixed solution was used.

Comparison 10 - Foomblin Z-AM as lubricating paint in Example 1
A magnetic tape was made in the same manner except that a 1 wt % ZS90 solution was used.

Dokaho λ Stearic acid Q, 1 as a lubricating paint in Example 1
A magnetic tape was made in the same manner except that a wt% isopropyl alcohol (IPA) solution was used.

Ratio m A magnetic tape was produced in the same manner as in Example 1, except that the formation of the lubricating layer was omitted.

Application 1"1 A polyester film with a thickness of 10 μm was set in a vacuum evaporation device, and 008ON was applied under a vacuum of 10-" Torr.
The i20 alloy was heated and evaporated to form a 2000-thick CoNi ferromagnetic metal thin film layer on the polyester film. Thereafter, the sample was left in an oxygen atmosphere of 3 atm for 50 hours to form a Co passive film with a thickness of 50 mm on the ferromagnetic metal thin film magnetic layer. Next, the polyester film on which the ferromagnetic metal thin film layer was formed was set in a gravure coating device, and the surface on which the ferromagnetic metal thin film layer was formed was coated with an alkylfluoroalkyl urea Q, 1wt% ZS90 (Montegison Co., Ltd.) having the following structure as a lubricant coating. Co., Ltd.) solution was applied and dried to form a lubricating layer with a thickness of 150 mm on the ferromagnetic metal thin film layer. The tape was then cut to a specified width to make magnetic tape.

A magnetic tape was produced in the same manner as in Example 4, except that a 0.1 wt % ZS90 solution of an organic compound having the following structure was used as the lubricating paint.

Cln H37N CN C2H4C6F lsOH Point 111 Tortoise As the lubricating paint in Example 1, 0.1 wt% ZS was prepared by mixing the organic compound used in Example 4 and Fomblin Z-AM20Of (manufactured by Montegisson) at a weight ratio of 1:1.
A magnetic tape was made in the same manner except that 90 mixed solution was used.

Example 11 1- A polyester film with a thickness of 10 μm was set in a vacuum evaporation device, and 008ON was applied under a vacuum of 10-” Torr.
The i20 alloy was heated and evaporated to form a 2000-thick CoNi ferromagnetic metal thin film layer on the polyester film. Thereafter, the sample was left in an oxygen atmosphere of 3 atm for 50 hours to form a Co passive film with a thickness of 50 mm on the ferromagnetic metal thin film magnetic layer.

Next, the polyester film on which the ferromagnetic metal thin film layer was formed was set in a gravure coating device, and an organic compound Q having the following structure, 1wt% ZS90 (manufactured by Montegisson) was applied as a lubricant coating to the surface on which the ferromagnetic metal thin film layer was formed. The solution was applied and dried to form a 150 mm thick lubricating layer on the ferromagnetic metal thin film layer. After that, it was cut to a predetermined width to make magnetic tape.

C,H7CH=CHC,,H,0N-C-○CH2C7
F lsS Loss of IJt & A magnetic tape was produced in the same manner as in Example 7, except that a 0.1 wt % ZS90 solution of an organic compound having the following structure was used as the lubricating paint.

As the lubricating paint in Example 7, Q, 1wt% ZS, which was a mixture of the organic compound used in Example 7 and Fomblin Z-AM2001 (manufactured by Montegisson) at a weight ratio of 1:1.
A magnetic tape was made in the same manner except that 90 mixed solution was used.

A polyester film with a thickness of 10 μm was set in a vacuum evaporator and heated under a vacuum of IO-' Torr.

The 8ONi20 alloy was heated and evaporated to form a 2000 nm thick CoNi ferromagnetic metal thin film layer on the poly-IJ ester film. Thereafter, it was left in an oxygen atmosphere at 3 atm for 50 hours to form a Co passive state film with a thickness of 50 mm on the ferromagnetic metal thin film magnetic layer. Next, the polyester film on which the ferromagnetic metal thin film layer was formed was placed in a gravure coating device, and 1wt of alkylfluoroalkylchilurea Q having the following structure was applied to the surface on which the ferromagnetic metal thin film layer was formed as a lubricating paint.
%ZS90 (manufactured by Montegisson) solution was applied and dried to form a lubricating layer with a thickness of 150 mm on the ferromagnetic metal thin film layer. After that, it was cut to a predetermined width to make magnetic tape.

A magnetic tape was produced in the same manner as in Example 10, except that a 0.1 wt % ZS90 solution of alkylfluoroalkylthiourea having the following structure was used as the lubricating coating.

As the lubricating paint in Example 10, the alkylfluoroalkylthiourea used in Example 10 and Fomblin Z-AM2001 (manufactured by Montegisson) were mixed in a weight ratio of 1:
A magnetic tape was produced in the same manner except that the 0 and 1 wt% ZS90a solution mixed in step 1 was used.

Each of the magnetic tapes produced as described above was assembled into an 8 mm VTR cassette half with a 90-minute specification, and a running test was conducted using an actual machine. The evaluation is based on the total running time during which the playback output decreased by 8db (output deterioration time: Tl), the time during which the output decreased by 6db during still playback (still lifespan 2 T2), and the number of instantaneous clogging during the first playback (90 minutes). , and the degree of tape squeal.

The evaluation criteria for tape squealing was based on three levels: O: no squealing, △: occasionally squealing<, and ×: squealing. Also, immediately after fabrication and 60
The stability over time was evaluated based on the friction coefficient of the magnetic recording layer against a stainless steel pin after being left at 90% RH for two weeks. The results are shown in Table 1 below.

(The following is a blank space) The media of Examples 1 to 12 have long output deterioration time and still life, are excellent in durability, have little noise, and have no change in friction coefficient. On the other hand, Comparative Example 1 has high durability but has a lot of noise.
Comparative Example 2 has no squealing, but the friction coefficient changes greatly, and Comparative Example 3 has significantly inferior durability. Therefore, according to the present invention, a magnetic recording medium with excellent running stability can be obtained.

[Effects of the Invention] As explained above, the lubricating compound used in the magnetic recording medium of the present invention is a lubricating compound used in the magnetic recording layer surface.
It is compatible with all substances such as binders, rust preventives, and other lubricants (and can form a uniform lubricant film on the magnetic recording layer, resulting in high lubricity and durability.

Claims (6)

[Claims] (1) In a magnetic recording medium consisting of a nonmagnetic substrate and a magnetic recording layer, a lubricating layer containing at least one organic compound selected from the group consisting of the following formulas (I) to (IV) is provided on the magnetic recording layer. A magnetic recording medium characterized in that: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼( IV) (In the formula, n is an integer of 0 to 3, R is a substituted or unsubstituted aliphatic hydrocarbon group having 8 or more carbon atoms, and RF is a perfluoroalkyl group having 4 or more carbon atoms. be.) 2. The magnetic recording medium according to claim 1, wherein R is a linear aliphatic hydrocarbon group having 8 or more carbon atoms. 3. The magnetic recording medium according to claim 1, wherein R is an aliphatic hydrocarbon group containing 1 to 4 double bonds in the molecule. (4) The magnetic recording medium according to any one of claims 1 to 3, wherein some or all of the hydrogen atoms in the molecule of R are substituted with fluorine. (5) The magnetic recording medium according to claim 1, wherein the magnetic recording layer is a ferromagnetic metal thin film. (6) The magnetic recording medium according to claim 1, wherein the magnetic recording layer contains Co as a main component, and a Co passive layer is formed between the magnetic recording layer and the lubricating layer.