JPS6087432A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease running friction and to improve film strength and head touch characteristic by forming a magnetic layer of a continuous thin film type on a base body and forming a film consisting of a specific compd. on the magnetic layer. CONSTITUTION:A magnetic layer of a continuous thin film type is formed on a base body and a film consisting of the compd. expressed by the formula 1 is formed on the magnetic layer. The film is formed by vapor deposition of sputtering to <=0.3mum thickness. The component of the magnetic layer consists essentially of Co. More specifically said component contains Co or Co and 1-3 kinds among No, Cr and O. The weight ratio of Co/Ni is made >=1.5 in the case of contg. Ni and the weight ratio of Cr/(Co or Co+Ni) is made 0.001-0.1 in the case of contg. Cr. The atom ratio of O/(Co or Co+Ni) is made <=0.45 in the case of contg. O. The magnetic layer is preferably an assemblage of columnar crystal structural particles inclined at 20-60 deg. with the normal of the base body. The thickness of the magnetic layer is made 0.05-0.5mum.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. BACKGROUND OF THE INVENTION Technical Field The present invention relates to a magnetic recording medium, particularly to an improvement in a pcoat film of a magnetic recording medium having a continuous thin film type magnetic layer.

Prior art and its problems As magnetic recording media for video, audio, etc., media having a continuous thin film type magnetic layer are being actively developed because of their continuous nature when wound into tapes.

Due to its characteristics, the magnetic layer of such a continuous thin film type medium is made of Co, Co-Ni, or Co, which is formed by the so-called oblique deposition method, in which deposition is performed at a predetermined angle to the normal to the substrate.
-0, Co--Ni--, etc.-based vapor deposited films are most suitable.

However, such a magnetic layer has high running friction, low film strength, poor head touch, and especially low running durability, resulting in a decrease in output due to repeated running.

In addition, video media have a short durability in a still image mode called still.

Furthermore, there are many so-called dropouts.

Under these circumstances, top coat films of thinly deposited magnetic layers have been proposed.

For example, evaporated or coated films of straight-chain saturated fatty acids or their esters (JP-A-53-88704, JP-A-55-F)
113533, etc.).

However, all of the conventional top coat films have still produced unsatisfactory results in terms of running durability, still characteristics, dropout, and the like.

II. Purpose of the Invention The present invention was made in view of the above-mentioned circumstances, and its main purpose is to provide a material with low running friction, excellent film strength, lubricity, and t-touch properties, and high running durability. Another object of the present invention is to provide a magnetic recording medium having a continuous thin film type magnetic layer having a novel top coat film, which has high still durability and less occurrence of dropouts.

Such objects are achieved by the invention described below.

That is, the present invention has a continuous thin film type magnetic layer on a substrate, and on this magnetic layer,
A magnetic recording medium characterized by having a film made of a compound represented by the following formula.

Formula R2 R, -N-R3 (In the above formula, R1 represents a substituted or unsubstituted aryl group, alkylaryl group, arylalkyl group, or alkylarylalkyl group having 6 to 20 carbon atoms, R2 and R3 may be the same or different and each represents a hydrogen atom or a substituted or unsubstituted aryl group or alkyl group.) In the above formula, the present inventors have determined that R1=R2=H The use of a seven-chain linear alkylamine in a top coat film was proposed as an earlier application of this application (Japanese Patent Application No. 57-2
No. 34817), but the present invention has the same effect as the previous proposal.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

The magnetic recording medium of the present invention has a magnetic layer on a magnetic layer.

The magnetic layer may be of a continuous thin film type and usually contains cobalt, nickel, or these as main components.

In this case, in the present invention, CO is an essential component, and C
o, Co+Ni, Co+O, or Co+Ni+O
It is preferable to consist of.

That is, it may consist of CO alone, or it may consist of CO and Ni.

In the case of Co+Ni, the weight ratio of Co/Ni is
It is preferable that it is 1.5 or more.

Furthermore, in addition to CO or Co+Ni, 0 may be included. When 0 is included, more favorable results can be obtained in terms of electromagnetic conversion characteristics and running durability.

In such a case, the atomic ratio of O/Co (if Ni is not included) or O/(Co+Ni) is 0.45 or less,
It is preferable that the special index is 0.15 to 0.4.

On the other hand, the magnetic layer contains Co, Co+Ni.

If Co+O or Co+Ni+O contains Cr, even more favorable results will be obtained.

This is because electromagnetic conversion characteristics are improved, output and S/N ratio are improved, and film strength is further improved.

In such cases, Cr/Co (if Ni or not included)
Alternatively, the weight ratio of Cr/(Co+Ni) is o, oot
It is preferable that it is 0.1.

In this case, Cr/Co or C'r/(C.

When the weight ratio of +N i) is 0.005 to 0.05, even more favorable results can be obtained.

Note that such a magnetic layer may further contain other trace components, particularly transition metal elements such as Fe, Mn, V, Zr,
Nb, Ta, Mo.

W, Ti, Cu, Zn, etc. may be included.

Such a magnetic layer is preferably an aggregate of particles having a columnar crystal structure tilted with respect to the normal to the main surface of the substrate.
This improves electromagnetic conversion characteristics.

In such a case, the particles having a columnar crystal structure are preferably inclined within a range of 20 to 60' with respect to the normal to the main surface of the substrate.

Further, each columnar crystal grain usually has a length spanning the entire thickness direction of the magnetic layer, and its breadth is generally about 50 to 500.

Then, CO and Ni added as necessary.

Cr etc. constitute this columnar crystal itself, and 0
When 0 is added, 0 usually exists mainly in the form of oxide on the surface of each columnar crystal grain.

Such a magnetic layer is usually formed to a thickness of 0.05 to 0.5 μm.

In this case, the magnetic layer may be provided directly on the substrate, or may be provided on the substrate via an underlayer.

Further, although the magnetic layer is usually formed as a single layer, it may be formed by laminating a plurality of layers with an intermediate layer interposed therebetween as the case may be.

Such a magnetic layer is typically formed by a double evaporation method.

As the oblique evaporation method used, a known oblique evaporation method may be used, and the minimum value of the incident angle with respect to the normal to the substrate is preferably 30' or more.

Note that the vapor deposition conditions, post-treatment method, etc. may be in accordance with known conditions and methods. In this case, effective post-treatment methods include various known treatment methods for introducing O into the magnetic layer.

On such a magnetic layer, a center made of amine and shown in a bipedal manner is formed.

In the above formula, R1 is a substituted or unsubstituted aryl group, alkylaryl group, arylalkyl group, or alkylarylalkyl group having 6 to 20 carbon atoms.

If the number of carbon atoms in R1 is less than 6, running friction becomes critically large, running durability and still durability are critically reduced, and dropout is also critically increased.

Furthermore, when the number of carbon atoms in R1 exceeds 20, dropout increases critically.

Note that when R1 is an alkylaryl group, an arylalkyl group, or an alkylary-noalkyl group, and the number of carbon atoms is 7 to 20, the running friction is further reduced,
Driving durability is further improved and dropouts are further reduced.

Is R1 having such a number of carbon atoms an aryl group,
Alternatively, it is a group having an aryl part and an alkyl part.

In this case, the aryl group or aryl moiety is preferably phenyl.

Furthermore, the alkyl moiety may be present on the bond side of the aryl moiety, on the opposite side, or even on both sides. The alkyl moiety may be linear or branched.

Such an aryl group, alkylaryl group, arylalkyl group, or alkylarylalkyl group may be unsubstituted or substituted.

Moreover, in the case of a substituted product, the number of substituents may be one or more. And an aryl group, an alkyl part,
Any of the aryl moieties may be substituted.

Particularly suitable substituents include halogens such as chlorine, bromine, and fluorine, alkyl groups and aryl groups (phenyl groups) bonded directly or through appropriate substituents, and groups in which one or more of these are linked. There is.

In this case, suitable linking groups include oxy, carbonyl, oxycarbonyl, carbonyloxy, amide, carbamoyl, sulfonamide, and sulfamoyl groups. In such a substituent, the total number of carbon atoms including the number of carbon atoms of the alkyl or aryl substituents must be within the above range.

On the other hand, R2 and R3 may be the same or different, respectively.

Represents a hydrogen atom or a substituted or unsubstituted aryl group or alkyl group.

In this case, the total number of carbon atoms in R1, R2 and R3 is 44
It is preferable that it is below. This is because when the number exceeds 44, dropouts increase.

The alkyl group of R2 and/or R3 may be saturated or unsaturated, linear or branched, and may have a cyclic portion. good.

Further, as the aryl group, a phenyl group is preferable.

The alkyl group or aryl group of R2 and R3 may be unsubstituted or substituted with the same group as R1.

Each of these compounds may be synthesized and used according to a known method, or commercially available ones may be used.

Next, specific examples of the compound represented by the above formula will be given.

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To 4 to 22 evening JiA:! E The top coat film made of such an amine has a monomolecular layer or more and 0.3 gm or less, more preferably 0.005 to 0.
, 1 gm thick.

Preferably, such a top coat film is formed by vapor deposition or sputtering.

When using coating, etc., rather than vapor deposition or sputtering, it is difficult to form a layer with a uniform thickness.

Note that the conditions for vapor deposition or sputtering may be in accordance with known conditions.

Although there are no particular restrictions on the substrate used, a particularly flexible substrate, particularly one made of resin such as polyester, polyimide, polypropylene, etc., is preferred.

Further, the thickness thereof may be various, but it is particularly preferably 5 to 20 #Lm.

Then, R of the surface roughness height of the back surface of the magnetic layer forming surface
The MS value is preferably 0.05LL+a or more.

This improves electromagnetic conversion characteristics.

■Specific effects of the invention The magnetic recording medium of the present invention is useful as a magnetic recording medium for video, audio, etc.According to the present invention, an aryl group having 6 to 20 carbon atoms, an arylalkyl group, Since a top coat film made of an amine having an alkylaryl group or an alkylarylalkyl group is used, running friction is significantly reduced.

In addition, its film strength, lubricity, and resistance to damage and damage are extremely high.

For this reason, running durability and still durability are critically improved, and dropouts are critically reduced.

Such effects are equivalent to those obtained when an amine having a linear alkyl group is used.

■Specific embodiments of the invention Specific examples of the present invention will be described in detail below.

Examples CoNi alloy with Co/Ni weight ratio 4/1 and Co/Ni/Cr in ratio 75/2015
Samples AO and BO were prepared by forming a magnetic layer with a thickness of 0.2 gm on a polyethylene terephthalate (PET) film with a thickness of 10 μm by an oblique evaporation method using the CoNiCr alloy.

The incident angle in oblique evaporation is 45'', and the evaporation atmosphere is P.
=2 X I O-' P a , P o 2= l
Xr 10-'P a.

The obtained magnetic layers both have the corresponding alloy composition,
Both have O/(Co+Nj)=0.2 (atomic ratio), are inclined by about 400 to the normal to the main surface of the substrate, and have a minor axis of 0.
It was an aggregate of columnar crystal grains that grew over the entire thickness direction of Ol gm.

In addition, Auger spectroscopy analysis while performing ion milling revealed that CO was less near the surface, and 0 was chemically shifted, and there was a profile in which there was more 0 near the surface, with 0 bonding with metal on the surface of columnar particles. It was confirmed that it existed in this state.

Next, a top coat film of O,Ol p-m thickness shown in Table 1 was applied on the AO and BO magnetic layers in an atmosphere of FA, =4xlO-3P a using each rice organic compound as an evaporation source. forming samples AlNA3 and Bl
I got it.

In addition, the top coat film composition of the sample of the present invention in Table 1 is indicated by the positive sign of the specific example of the compound described above.

The following measurements were performed for each of these samples.

l) The dynamic friction coefficient of the running friction samples was measured at 40° C. and 80% relative humidity initially and after 50 baths.

2') Running Durability A 50-pass test was conducted on each sample using a commercially available VTR device, and the amount of reduction (dB) in the 4M)1z signal was measured.

3) Still fire resistance Using a commercially available VTR device, the time (minutes) until the image disappeared in still mode was measured.

4) Dropout An output drop of 16 dB or more per minute (dropouts/min) was measured.

These results are shown in Table 1.

From the results shown in Table 1, the effects of the present invention are clear.

Applicant TDC Co., Ltd. Agent Patent Attorney Yo Ishii -

Claims (8)

[Claims] (1) A magnetic recording medium characterized by having a continuous thin film type magnetic layer on a substrate, and having a film made of a compound represented by the following formula on this magnetic layer. Formula R2 ■ R1-N-R3 (In the above formula, R1 represents a substituted or unsubstituted aryl group, alkylaryl group, arylalkyl group, or alkylarylalkyl group having 6 to 2 carbon atoms, R2 and R3 may be the same or different and each represents a hydrogen atom or a substituted or unsubstituted aryl group or alkyl group.) (2) The magnetic recording medium according to claim 1q4, wherein the film is a vapor deposited or sputtered film. (3) The magnetic recording medium according to claim 1 or 2, wherein the film has a thickness of 0.3 gm or less. (4) The magnetic layer is Co, or Co and Ni,
The magnetic recording medium according to any one of claims 1 to 3, containing one to three of Cr and O. (5) The magnetic recording medium according to claim 4, wherein the magnetic layer contains Ni and has a Co/Ni weight ratio of 1.5 or more. (6) The magnetic recording medium according to claim 4 or 5, wherein the magnetic layer contains Cr and has a quantitative ratio of Cr/(C. or Co+Ni) of 0.001 to 0.1. . (7) The magnetic layer contains 0, 0/(Co or cc+
The magnetic recording medium according to any one of claims 4 to 6, wherein the atomic ratio of +Ni) is 0.45 or less. (8) The magnetic recording medium according to any one of claims 1 to 7, wherein the magnetic layer is an aggregate of columnar crystal grains tilted with respect to the normal to the substrate. (9) The magnetic recording medium according to any one of claims 1 to 8, wherein the magnetic layer has a thickness of 0.05 to 0.5 lm.