JPS5990231A - Magnetic recording medium and its manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Industrial applications Magnetic recording media such as magnetic tapes and magnetic disks.

Structures of conventional examples and their problems Polyester is produced by depositing thin films of iron, cobalt, nickel, alloys containing these as main components, or their oxides using vacuum deposition methods such as vacuum deposition, sputtering, and ion blasting. film.

Ferromagnetic thin film magnetic recording bodies formed on polymer film substrates such as polyimide films can dramatically improve recording density compared to conventional coated magnetic recording media. In order to increase the density, it is necessary to make the surface of the magnetic recording medium non-slip and to reduce spacing loss as much as possible.

However, if the surface is made too flat, it will cause problems with head touch and running surface. In the rotating head video tape recorder system that has become popular in the general market in recent years, if we want to further increase the magnetic tape recording density, it will be necessary to use ferromagnetic thin film magnetic recording media.
The practical features of magnetic recording media that are especially required for such 7-stem systems include good head touch and head surface abrasion resistance, which prevents head clogging and φIll<, and which is suitable for rotary heads. The goal is to achieve stable running performance (low friction, good wear resistance) at the contact points with cylinders, tape guide bosses, audio fixed heads, etc. Ferromagnetic 1. The surface properties of the gamma film type magnetic recording medium are very small, with a magnetic layer thickness of about 0.1 to 0.5 .mu.m, and almost all depend on the surface shape of the substrate, ie, the plastinokfilno. Therefore, many proposals have been made regarding the surface properties of films. An example of this is
3-116115, JP 63-128683, JP 154-94574, JP 66-
It is fully described in JP-A No. 10456, JP-A-66-16937, etc. In all of these examples, the surface shape is relatively finely and uniformly roughened, for example, wrinkle-like protrusions are formed or waves are formed.

By forming earthworm-like or granular protrusions,
The aim is to improve head touch and running performance all at once. However, the contact width of the rotating gutter for video is narrow, less than a few hundred microns, and the relative speed with the magnetic tape is as fast as several meters and seven seconds, whereas the friction in the magnetic tape running system is slow ( Because of the large area contact (several centimeters 7 seconds), it is thought that the optimal magnetic tape surface for these partners is not uniform. Generally speaking, as a measure to prevent head clogging, it is necessary to have a surface that has some abrasive effect on the head. From this viewpoint, the present inventors have arrived at the present invention as a result of studying the optimal surface properties to meet these requirements.

OBJECTS OF THE INVENTION An object of the present invention is to provide a ferromagnetic thin film magnetic recording medium that has a small coefficient of friction, is less likely to cause head clogging, and has stable durability, and a method for manufacturing the same.

Structure of the Invention First, here, a plastic film base material is usually handled in a rolled-up state, and in this state, the surface of the film base material is in local contact with the surface of a mating film base material. become. The opposing film base surfaces are
If both have been cleaned and activated by plasma treatment or have good adhesion, they will adhere at the areas where they are in contact, and when the film is pulled out from the roll, the bonded area will break and the breakage will occur. Depending on the degree of damage, if the local fracture stops, fine ridges will be formed on the surface of the film substrate, and if the fracture does not stop at the local fracture and propagates to other parts of the film, the film will not be ruptured. Sign.

Now, the present invention is characterized in that a ferromagnetic thin film is formed on the fine protrusions of the former type, and as a means to stably cause only the former type of destruction, it is possible to It is characterized by employing plasma treatment.

DESCRIPTION OF THE EMBODIMENTS The plastic film base material used in the present invention includes a polyester film made of polyethylene terephthalate or a copolymer or mixture thereof, polyethylene terephthalate or a copolymer or mixture thereof, a base material, A polyimide film base material such as polyesterimide or polyimide, an aromatic polyamide film, etc., with good surface smoothness and wrinkled or wavy shape on at least one side.
Particularly desirable are those having granular, worm-like, etc. fine projections.

The conditions for plasma treatment include vacuum [: 1o'~1
0' Torr, Frequency: Direct 14 (,~44 MJ
h r 71i Pressure: 10v~3KV Current density:
1 to 6oOμAp-p'/unit area of electrode, atmosphere: residual air, oxygen, argon,
Nitrogen, carbon dioxide, a mixture thereof, etc. are preferable, but are not necessarily limited to these. Both sides of the plastic film substrate may be plasma-treated at the same time, or one side may be sequentially treated. What is important is that the plastic film be rolled into a roll after both sides have been subjected to plasma coating. It is desirable that the winding after plasma treatment be carried out in a vacuum.

The ferromagnetic thin film can be formed by conventional methods such as vacuum evaporation, ion blating, and sputtering.
It is desirable to set a plasma-treated roll-shaped plastic film base material in a ferromagnetic thin film forming apparatus and immediately form a thin layer on the surface of the film base material after pulling it out from the roll state. When forming a thin film after once rewinding a film base in a roll state in the atmosphere, there is a possibility that the minute dents generated when the film base material is peeled off may be reduced by half due to a relaxation phenomenon.

1, the ferromagnetic thin film is the most effective way to utilize the minute cracks produced during exfoliation.

This is a case where Fe or an alloy containing Fe or an alloy containing Fe as a main component is formed by oblique vapor deposition in an oxygen atmosphere. Regarding these vapor depositions, Japanese Patent Publication No. 56-23208,! As described in Publication No. 1, Publication No. 57-2977Q, Japanese Unexamined Patent Publication No. 56-16014, and Japanese Unexamined Patent Publication No. 57-37719, the effects of the present invention are as follows: ” - more preferably 30° or more, and the resulting film thickness is 4oO
This becomes noticeable when the oxygen content (atomic ratio of oxygen to ferromagnetic metal) increases. In other words, in the above case, the ferromagnetic + J7. 'i is reflected in the surface properties of the film.

In carrying out the present invention, various types of lubrication-containing layers, antirust agent-containing layers, etc. may be provided on the surface of the magnetic layer or the back surface of the plastic film substrate by known means.

Next, the present invention will be explained in more detail.

Example 18 Polyester stretched film base material g' with good smoothness and almost no particulates due to polymerization catalyst residue
A mixed solution of phenol and carbon tetrachloride of polyethylene tereftate was applied to one side of the film (thickness 12 μm) and dried to form wrinkle-like protrusions (surface roughness i Rmax - 0.06 μm mouth 1. Wrinkle interval 2 μm). Both sides were placed between SUS electrodes in an oxygen vacuum of 1 x 10 Torr.
Plasma treatment is performed by passing through the plasma generated by applying a 60 Hz alternating current of V, and then the film is wound up into a roll. (
1×10 TO
A ferromagnetic thin film (thickness: 1000 mm) was formed continuously from the high incidence side by oblique evaporation along a cylindrical roll in an oxygen atmosphere of 100 mm at an incident angle of 300 mm or more. Thereafter, a graphite-containing Evoquin resin slippery thin film was formed on the back surface of the film base material in the atmosphere, and then the tape was slit to the width of the tape to obtain a magnetic tape sample. On the protrusions of the wrinkle-like protrusions on the surface of the magnetic layer, there are fine granular protrusions (average diameter 1000 mm, height approximately 200 mm) caused by adhesive peeling.
Approximately 1,000,000 particles per person and surface were present. This sample will be referred to as sample A.

Example 2. Sample B is a sample obtained in Example 1 when a ferromagnetic thin film was provided on the smooth surface side of the film L and profiteering. The surface of the magnetic layer (which should originally be smooth) has fine granular projections ('l' average surface diameter of 100 mm) caused by adhesive peeling.
0 people, height approx. 200 people 9 Number of pieces per mJ of surface approx. 10
00,000 pieces) were concentrated in the area where the protrusions of the wrinkle-like processes were in contact.

Comparative example 1. In Example 1, when the plasma treatment was applied only to the surface on which the magnetic layer was to be formed, that is, the surface on which the wrinkled projections were formed, no projections other than the wrinkled projection pattern were observed on the surface of the obtained magnetic layer.

This sample is designated as C.

Example 3. A method of applying and curing a thermosetting emulsion resin solution mainly consisting of an epoxy-modified noricorn emulsion to both surfaces of the film during the stretching film forming process using a polynisder polymer containing almost no particulates due to the presence of a combination catalyst. Using a polyester film having earthworm-like protrusions made of a cured emulsion resin on both sides produced in Example 1, both sides were subjected to plasma treatment and rolled under the same conditions as in Example 1.

Magnetic layer is deposited, and the back side is coated with a graphite-containing resin layer.

The magnetic Tesos test tube 1 obtained by sequentially performing slitting is used as a sample. The surface of this magnetic layer has earthworm-like protrusions (protrusion height approximately 200 mm, filth/widthwise protrusion spacing approximately 1 μm).
), fine granular protuberance aggregates (average particle size: 600 particles, 1 particle height: approximately 160 particles, 5 particles) were formed locally on the protrusions of the earthworm-like protrusions. was.

Comparative example 2. In Example 3, when the magnetic layer was continuously vapor-deposited immediately after plasma treatment without being wound, the surface of the magnetic layer had the following properties:
No fine protrusions were observed other than the earthworm-like protrusion pattern. Let this trial be E.

Example 4. Using Samples A-K, an image quality test was conducted using a test video recorder at 26° C. and 65% R and H, and the still life was also measured. Man/ko, 25°C85% R
RFF and image quality test I were carried out in ,H, and 65th section R,H
We investigated the deterioration of image quality caused by noise and other factors in high humidity environments compared to those in high humidity environments. The results are shown in the table below. Note that trial C1E is a comparative example.

Effects of the Invention As is clear from the second point, the magnetic recording medium of the present invention has particularly good surface 1 abrasion resistance due to the head of a video magnetic tape and running stability in high humidity. It is extremely practical.

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Claims (2)

[Claims] (1) A magnetic recording medium characterized in that a ferromagnetic thin film is formed on a base surface of a plastic film that locally adheres to the other surface when the plastic film is rolled up and has minute protrusions that occur when the film is peeled off. (2) Plasma treatment on both sides of plastic film profiteering” J1! A method for manufacturing a magnetic recording medium, which comprises: applying and rolling the plastic film, then peeling it off, and then forming a ferromagnetic thin film on the surface of the plastic film base material.