JPS5868225A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance the wear resistance and running stability, by forming a ferromagnetic thin film on a plastic film having a surface provided with granular, wrinkly or vermicular protrusions. CONSTITUTION:A ferromagnetic thin film 5, 5' is formed on the surfaces of granular, wrinkly or vermicular protrusions 4, 4' having surface projections 3, 3' due to residue of polymn. catalyst or added fine particles 2, 2'. The height of the projections 3, 3' is <=2,000Angstrom and the average density of projections having 300- 2,000Angstrom height is 10-10,000 per 1mm.<2> surface area.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ferromagnetic thin film magnetic recording medium suitable for use as a magnetic tape for a rotary head type video tape recorder, for example, and which satisfies both abrasion resistance due to the magnetic head and running stability. This is something that we are trying to encourage.

Polymer films such as polyester films and polyimide films are produced using thin films of iron, cobalt, nickel, alloys containing these as main components, or their oxides using vacuum deposition methods such as vacuum evaporation, sputtering, and ion blasting. Ferromagnetic thin-film magnetic recording media formed on a substrate can dramatically improve recording density compared to conventional coating-type magnetic recording media. It is necessary to smooth the surface of the medium to reduce spacing loss as much as possible.

However, if the surface is made too flat, it will cause problems in head touch and running surface. In order to further improve the magnetic tape recording density in rotating head video tape recorder systems that have become popular in the general market in recent years, it is necessary to apply ferromagnetic thin film magnetic recording media. Practical performance requirements for magnetic recording media include good head touch and head abrasion resistance, resistance to head clogging, and good contact with rotating head cylinders, tape guide posts, audio fixed heads, etc. The aim is to achieve stable running performance (low friction, good wear resistance) in the parts. The surface properties of ferromagnetic thin-film magnetic recording media are such that the magnetic layer thickness is 0.1 to
Since it is very small, about 0.6 μm, it almost entirely depends on the surface shape of the substrate, ie, the plastic film. Therefore, many proposals have been made regarding the surface properties of films. An example is JP-A-53-116115
Publication No. 128683/1983, Japanese Patent Application Laid-open No. 1983-128683
-94574 publication, JP-A-56-10455 publication,
It is described in Japanese Unexamined Patent Publication No. 16937/1983.

In all of these examples, the head touch and running performance are improved at once by roughening the surface shape relatively finely and uniformly, for example by forming wrinkle-like protrusions, earthworm-like or granular protrusions. This is an attempt to improve. However, whereas the video rotary head has a narrow contact width of several hundred microns or less and a relative speed of several meters and seven seconds with the magnetic tape, the friction in the magnetic tape running system is slow (a few centimeters). 7 seconds) Because of the large-area contact, it is thought that the optimal magnetic tape surface properties for these types of contact are not uniform. moreover,
As a measure to prevent head clogging, the present invention was arrived at as a result of examining the optimum surface properties to meet these requirements from the viewpoint of polishing the head to some extent.

That is, the present invention provides a ferromagnetic thin-film magnetic recording medium whose surface has a height of 5 to 300 people and an interval of 0.1 to 10
This invention relates to a magnetic recording medium characterized by having granular, wrinkled, or earthworm-like protrusions of μm in size, and an average of 10 to 10,000 protuberances per 1 surface area with a height of 300 to 2,000 μm higher than the protrusions. The former, granular, wrinkled, or earthworm-like protrusions, are used to deal with head wear and tear, while the latter's protrusions prevent head clogging and improve running performance. .

This will be explained in more detail below. In embodying the present invention, first, as a film substrate on which a ferromagnetic thin film is to be formed, the surface of the magnetic surface side is made of grains, wrinkles, or earthworms with a height of 60 to 300 people and an interval of 0.1 to 10 μm. A ridge or protrusion higher than the protrusion with a height of 300 to 2000 and an average of 10 to 10,000 ridges or protrusions per surface area is prepared, and a ferromagnetic thin film is deposited on it in a vacuum. Form. As the film substrate, linear polyesters such as polyethylene terephthalate, polytetramethylene terephthalate, polyethylene-2,6 naphlate, and cellulose triacetate are used.

Films made of cellulose such as cellulose acetate butyrate, heat-resistant polymers such as borimide, polyesterimide, aromatic polyamide, etc. are suitable, and among these, the most suitable from a practical standpoint is a stretched polyethylene terephthalate film. As a means for making their surface properties suitable for the present invention, for example, they have surface ridges based on polymerization catalyst residues or added fine particles, and the height of the ridges is 2,000 or less. , 300 to 2000, a film or a material thereof having a surface having an average density of 10 to 10,000 bumps per surface area is prepared, and the method is disclosed in JP-A-53-116115 and JP-A-53-1.
By forming a specific resin thin film on the surface of the film during or after the film formation as described in Japanese Patent Application Laid-Open No. 56-10455,
Some produce granular, wrinkled, or worm-like protrusions with a height of 5o to 3o and an interval of 0.1 to 1oμm. Figure 1 shows
FIG. 2 is a sectional view in the thickness direction of a magnetic recording medium, which is an embodiment of the present invention, in which a ferromagnetic thin film is formed on a substrate film obtained by such means.

In FIG. 1, 1 is a substrate film, 2 is fine particles contained in the substrate film 1, 3 is a ridge on the surface formed by protruding fine particles 2, 4 is a granular protrusion formed on the surface, 5
is a ferromagnetic thin film layer formed to a uniform thickness on the surface including the granular projections 4. In this example, the height of the protrusions and their density can be changed by controlling the size and amount of fine particles in the film substrate raw material resin, and the height of the granular protrusions and the spacing between them can be changed by controlling the size and amount of fine particles in the film substrate raw resin. It can be changed by controlling the composition of the resin liquid, drying, (stretching), curing conditions, etc.

The height of protrusions and protrusions in the present invention is JIS-B12O3
The value is expressed as the distance from the top of the uneven surface to the bottom of the valley according to the maximum surface roughness Rwax specified in
(manufactured by YLOR-HOBSON). Also, the number of ridges or protrusions per surface area is
Optical microscope with differential interference interference (OPTIPHOT, XP-NR
This can be obtained by randomly sampling at least 1o field of view at a magnification of 50 to 400 times with a model 1 (manufactured by Nippon Kogaku Kogyo), measuring the number of ridges or protrusions present in those fields, and calculating the average value per 1. It is something that can be done.

In the present invention, the thickness of the granular, wrinkled, or earthworm-like protrusions is 60 to 300 people in height with an interval of 0.1 to 1.
If the range of 0 μm is suitable and the height is less than 50 people,
Alternatively, if the interval is smaller than 0.1 μm, it becomes difficult to obtain a surface roughening effect, and wear caused by the rotating head increases, resulting in a decrease in service life. Furthermore, if the height is 300 m or more, the output will decrease, and if the ζ interval is 10 μm or more, it will cause noise. On the surface, within the above range,
A magnetic recording medium having granular, wrinkled, or earthworm-like protrusions has good runnability in a video recorder in normal humidity, but the humidity is so%R,H.

In this case, running delays and stinox knobs are likely to occur in a part of the fixed cylinder of the rotary head or in the tape guide post, causing jitter and noise, and in extreme cases, making it impossible to run. To prevent and improve such phenomena, the above, grainy, wrinkled.

Or, in addition to earthworm-like protrusions, they are taller, with an average of 10 to 10.
000 protrusions or protrusions are preferably present.

In this case, if the height is less than 300 Å or the average density is less than 10 pieces/-, it is difficult to obtain this effect, and if it is more than 200 Å or more than 10,000 pieces, noise will be generated. The most preferable range is a height of 300 to 1,000 pieces and an average density of 100 to 6,000 pieces/-. These protrusions or protrusions have the effect of abrading the head surface when they come into contact with a high-speed rotating spatula or blade, that is, they have the effect of preventing head clogging, and their presence improves the life of the metal. . In FIG. 1, the granular protrusions are present on the ridges, but in the ridge portions as shown in FIG. 2, the ferromagnetic thin film may be formed directly on the ridges. Note that the symbols attached to each element in FIG. 2 correspond to those in FIG. 1 without one or two, so the explanation of each symbol will be omitted.

To form a ferromagnetic thin film on a substrate film, for example, a ferromagnetic thin film of iron, cobalt, nickel, or an alloy thereof can be directly deposited on the substrate by vacuum evaporation, ion blasting, sputtering, etc. , formed through a base thin film of chromium or the like. Also,
These non-magnetic thin films can also be inserted as a separator between the magnetic thin films. In these cases, by containing oxygen in the ferromagnetic thin film and the underlying thin film (partially oxidizing the metal), it is possible to further improve the adhesion strength with the substrate film and improve the still life. If necessary, the surface of the ferromagnetic thin film can be overcoated with various non-magnetic materials, and the back side of the substrate film can be coated with various known measures to improve running performance. Detailed description of the invention.

Using several types of polyester polymers with different shapes and contents of fine particles caused by polymerization catalyst residue, a thermosetting aqueous emulsion resin liquid mainly consisting of an epoxy-modified silicone emulsion is applied and cured on both sides of the film during the stretching process. Polyester biaxially stretched films (thickness 12 μm) having earthworm-like protrusions made of cured emulsion resin and protuberances based on polyester polymerization catalyst residue on both surfaces, produced by the method of Twelve types of samples were selected, and they were connected to form a long roll. Cobalt and nickel alloy (Ni2wt%) was obliquely vapor-deposited on one side of the long roll in the presence of a trace amount of oxygen in a vacuum evaporator to a thickness of 0.1 μm. After forming a ferromagnetic thin film layer of Obtained. The surface shapes of these samples are shown in the table. These samples were assembled into cassettes, and an image quality test was conducted using a commercially available home video recorder at 25° C. and 65% R, H, and the methyl lifespan was also measured. Also, 26°C85%R
An image quality test was conducted again in , H, and compared with the case of 66% R, 1 (, 9) to examine the deterioration in image quality due to jitter and stick-slip under high humidity.The results are also listed in the table. Note that among the samples in the table, Fbl, Fhll, and No. 12 are outside the scope of the present invention and are listed as comparative examples.

(Margin below) The camera has a long still life and shows no deterioration in image quality under high humidity.

As described above, the magnetic recording medium according to the present invention has both head wear resistance and running stability as a video magnetic tape, and has extremely high practical value.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a magnetic recording medium that is an embodiment of the present invention, respectively. 1.1'...Substrate film, 2.2'...
・・Fine particles, 3.3′・・・・Protuberance, 4.4′・・
...Grain projections, 6,6'...Ferromagnetic thin film layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure I! Figure 2

Claims (1)

[Claims] Grainy, wrinkled, and rim pads with a height of 50 to 300 mm on the surface 1)
A magnetic recording medium characterized in that a ferromagnetic layer is provided on a plastic film formed of 10 to 10,000 pieces.