JPH0191321A - Discoid magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the recording-reproducing performance of a medium in a high frequency band and to improve the frequency characteristics over the entire band by forming an applied layer contg. magnetic particles as a lower layer on a support and a magnetic thin film as an upper layer on the lower layer. CONSTITUTION:A magnetic coating material is applied on a support 16 for a floppy disk 14 to form a magnetic applied layer 17. A magnetic thin film 18 made practically of a magnetic material is laminated on the layer 17 to form a magnetic recording layer 12 and a magnetic layer 13. The resulting floppy disk has satisfactory recording-reproducing performance in a low frequency band, the recording-reproducing performance in a high frequency band is improved and the frequency characteristics can be improved over the entire band.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a disk-shaped magnetic recording medium, particularly to a floppy disk such as a video floppy disk.

Conventional technology Electronic still cameras that magnetically record still images use small flexible magnetic disks.
For example, 25 frames or more of still images can be recorded on one side of the disk. These electronic still cameras have advantages over cameras using silver halide film, such as requiring no development, being reusable, and being easy to transmit.

5 and 6, a conventional video floppy cartridge 1 is shown. This cartridge 1 is
Plastic cartridge body 2 called shell
Openings 3 are formed on both sides of the main body, and the floppy disk 4 inside faces the openings 3 (However, in FIG. 5, only one opening 3 is shown with a broken line, but the other opening is (exists on the opposite side of 2). The opening 3 is normally shielded by a metal shutter 5 that has a U-shaped cross section when the disk is not in use, and the disk 4 is not exposed. However, when the disk is being driven (magnetic recording), the shutter 5 is closed. is moved to the imaginary line position, and the recording surface of the disk 2 is exposed through the opened opening 3. Note that the disk 4 is rotatably housed within the main body 2 while being fixed to a center hub 6 attached to a spindle on the driver side.

When driving such a video floppy disk 4, the opening 3 is opened (that is, the shutter 5 is opened), and in this open position, the magnetic head is brought into contact with the disk surface from the bottom side, and the pad is brought into contact with the disk surface from the top side. To an appropriate place
It is designed to generate 7 dots. Normally, the disk 4 is rotated before the shutter 5 is opened, and the shutter 5 is opened when the rotation speed reaches a certain level.

However, since the conventional disk 4 has a magnetic recording layer formed by coating a magnetic paint on a polymer support, the frequency characteristics in the low frequency range are relatively good, but the frequency characteristics in the high frequency range are poor. It has poor performance and is insufficient for high frequency recording.

C.5 Purpose of the Invention An object of the present invention is to provide a disc-shaped magnetic recording medium that has good frequency characteristics not only in the low frequency region but also in the high frequency region and has improved recording and reproducing performance over the entire range. .

21 Structure of the invention and its effects, that is, the present invention provides a magnetic particle coating layer formed by coating a magnetic paint, and a magnetic thin film made of substantially only magnetic material or a magnetic thin film via an intermediate layer on a support. This relates to disc-shaped magnetic recording media that are sequentially stacked.

According to the present invention, since the above-mentioned magnetic particle coating layer is first provided as a lower layer on the support, the recording and reproduction performance in the low frequency range of the medium is good, and at the same time, the above-mentioned magnetic particle coating layer is provided on the magnetic particle coating layer. Since the magnetic thin film is provided as an upper layer, the recording and reproducing performance of the medium in the high frequency range is also improved, and the frequency characteristics can be improved over the entire range. The magnetic particle coating layer described above generally has magnetic particles dispersed in a binder material, so the recording wavelength is long (for low frequencies), and the magnetic thin film described above has a large packing density of magnetic particles, so the recording wavelength is long. This is because it shortens (for high frequencies).

E, Example The present invention will be explained in detail below.

FIG. 2 shows a state in which the flexible video floppy disk 14 according to the present invention is being driven, that is, a state in which the magnetic heel 10 is in contact with the lower surface and the pad 11 is in contact with the upper surface. In this case, as shown in an enlarged view in FIG. 1, the magnetic recording layer 12 is attached to the head 10, and the other magnetic layer 13 of the support 16 (this is not used for magnetic recording but is provided to prevent curling of the medium). ing.

) will be brought into contact with the pad 11. Arrow 15 indicates the direction of disk travel (rotation). The floppy disk 14 is housed in a cartridge similar to the example shown in FIGS. 5 and 6, and is driven in the same manner for recording/reproduction.

What should be noted here is that the above-mentioned magnetic recording layer 12 is formed by applying a magnetic particle coating layer 1 by applying a magnetic paint based on the present invention.
7 and a magnetic thin film 18 made of substantially only magnetic material are sequentially laminated on the support 16.

The magnetic thin film 18 may be formed directly on the coating layer 17, or may be formed via an intermediate layer. Note that the magnetic layer 1
3 may similarly consist of a laminate of a magnetic particle coating layer 17 and a magnetic thin film 18.

The magnetic particles used in the magnetic particle coating layer 17 and the magnetic thin film 18 are metal magnetic powders, for example, metals such as Fe, Co, and Ni, or Fe-Co- and Fe-Ni.

Fe-A j! %CoNl,,FeC
o -N'i %Fe -An-Ni ,,Fe-Rh
, Fe-Cu.

Co-CLI% Co-Au, Co-YSC
o-La.

Co-Pr% Co-Gd, Co-3m
, Co-Pt.

Ni-Cu% Mn-Bi, Mn-3b%
Mn-AA, Fe-Cr, Co-Cr,
Ni-Cr, Co-Ni-Cr, Fe
A material made of a ferromagnetic alloy such as -Co-Cr, Fe-Co-Ni-Cr, etc. is used.

Among these, an alloy containing Co2%Ni as a main component is preferable. The thickness of the magnetic thin film is preferably 300 to 800. The method of magnetizing this thin film is preferably an in-plane magnetization type, and an intermediate layer may be provided between the coating layer and the thin film layer if necessary.

Further, the intermediate layer may be formed of a single layer of chromium, or may be formed of Cr and other elements (for example, Zn, Ti, Go, etc.).
). That y7 is 200~2
000 people is preferred.

The magnetic particle coating layer 17 further contains a lubricant (for example, carbon blank, silicone oil, graphite, molybdenum disulfide, tungsten disulfide, carbon atoms 12 to 20).
Monobasic fatty acids (for example, stearic acid), fatty acid esters having 3 to 40 carbon atoms, etc.), antistatic agents (for example, carbon black, graphite), etc. may be added. In addition to the above-mentioned aluminum oxide and chromium oxide, non-magnetic abrasive particles include artificial corundum, fused alumina, silicon carbide, chromium oxide, diamond, artificial diamond, garnet, emery (main components: corundum and magnetite), etc. is used.

Furthermore, at least polyurethane can be used as the binder resin for this coating layer 17, which can be synthesized by reacting polyol and polyisocyanate. If a phenoxy resin and/or a vinyl chloride copolymer is contained together with polyurethane, the dispersibility of the magnetic powder will be improved when applied to a magnetic layer, and its mechanical strength will be increased. However, if only the phenoxy resin and/or the vinyl chloride copolymer is used, the layer becomes too hard, but this can be prevented by containing polyurethane, and the adhesion to the support or base layer is improved. In addition to the above, cellulose resins, thermoplastic resins, thermosetting resins, reactive resins, and electron beam curable resins may be used as the binder resin.

Further, the magnetic recording medium shown in FIG. 1 may be provided with an undercoat layer (not shown) between the magnetic N12.13 and the support 16, or may not be provided with an undercoat layer. (Same below). The support may also be subjected to corona discharge treatment.

Further, as a material for the support body 16, plastics such as polyethylene terephthalate and polypropylene are used.

The magnetic disk according to the present invention can be applied not only to still images, but also to moving images (particularly frame-by-frame), and even as external memory for computers. Furthermore,
It is also applicable to other types of floppy disks.

Further, the disk 14 may be of a double-sided recording type or a single-sided recording type (in this case, the magnetic layer 113 may or may not be formed as described above).

In FIG. 1, the layer thickness of the coating layer 17 is 1 to 5 μm,
The thickness of the thin film 18 is preferably 300 to 800. If the coating layer 17 is too thick, the effective recording efficiency will be wasted, and if it is too thin, the film strength will decrease and the recording performance will tend to deteriorate. If the thin film 18 is too thick, it will take time to form the film as described below. If it is too thin, it is undesirable from both film strength and recording characteristics. Note that a protective lubricant layer (
(not shown) is preferably provided. This lubricating layer may be a coating layer containing a lubricant in the binder resin as described above.

FIG. 3 shows a process for forming the coating layer 17.

That is, the support 16 wound around the supply roll 22 is conveyed to the magnetic paint application means 23, and a coating film containing magnetic particles is formed thereon. Subsequently, the coating film is passed through a non-orientation magnetic field 24 for non-orientation, and then passed through a drying means 25 to dry the coating film, thereby forming a magnetic layer 17. Next, if necessary, the sheet is guided to a calender section 26 consisting of a combination of calender rolls 26a, subjected to calender treatment, and wound onto a winding roll 32. In the figure, 23a is an opposing roll for coating, 23b is a blade for scraping off excess paint, and 23c is a magnetic paint. Further, 27 is the longitudinal direction in which the magnetic paint is applied (ie, the direction in which the support l is conveyed).

After this step, the support 16 (with the coating layer 17) is unwound from the unwinding roll 32 inside the vacuum chamber 31 in the vacuum evaporation apparatus shown in FIG.
The winding roller 35 travels along the circumferential surface of the winding roller 35 and is wound around the winding roll 35. On the other hand, on the film 33 passing through the rotating drum 34, a magnetic metal 38 heated and evaporated from the crucible 36 is selectively deposited on the film 16 by a shutter 37, and a magnetic layer made of this metal magnetic thin film is formed in one day. The vapor-deposited film 39 is wound onto the take-up roll 35. - In this vapor deposition, for example, the thickness is 32 μm (for video floppy, 75 μl I+ for normal floppy) and the width is 160 μm.
++ 500 Cr intermediate layer on UW polyethylene terephthalate film 16 and Co − on Cr intermediate layer.
Ni-Cr Eil film 18 is ff sa7!1 (50
A flat surface was deposited so that there were 0 people. At this time, the evaporation source 38
The materials used included Co: 62.5% by weight, Ni: 30% by weight, and Cr: 5% by weight.

Next, this vapor-deposited film is subjected to the next step of punching out a disk shape (not shown). Thereafter, the floppy disk 14 is obtained by burnish polishing.

In addition to the above-mentioned vapor deposition, the thin film 18 can also be formed by other physical film forming methods such as a sputtering method, an ion blasting method, and a plating method.

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

After the components listed below were dispersed in a sand mill, the magnetic paint was filtered through a 1 μm filter, coated on both sides to a thickness of 5 μm on a 32 μm support, supercalendered, and wound up.

Metal magnetic powder 100 parts by weight Polyurethane 5 Phenoxy resin 5 Lecithin 3 Alumina 5.

Carbon black 3 Myristic acid 2 Butyl stearate l Cyclohexanone 100 Methyl ethyl ketone 100 Toluene 100 Isocyanate 3 Next, in a vacuum evaporation apparatus, a Cr intermediate layer was coated with 500 Cr.
A magnetic thin film of 800 layers was formed on the coating layer by plane deposition on the intermediate layer using an evaporation source containing 62.5% by weight of Co, 30% by weight of Ni, and 5% by weight of Cr.

Thereafter, it was punched out to a diameter of 471 mm to produce a video floppy.

The performance of the video floppy disk obtained as described above is compared with that of a conventional product (without magnetic thin film) and is shown in the table below.

From these results, it can be seen that the disk with the magnetic layer formed according to the present invention has high output, high recording density, and good frequency characteristics, whereas the conventional product has poor frequency characteristics, especially in the high range.

The embodiments described above can be further modified based on the technical idea of the present invention.

[Brief explanation of the drawing]

1 to 4 show embodiments of the present invention. FIG. 1 is a partial cross-sectional view of a floppy disk, FIG. 2 is a schematic diagram of the main parts of a disk drive, and FIG. 3 is a magnetic A schematic view of the step of forming a particle coating layer, and FIG. 4 is a sectional view of a vacuum evaporation apparatus. FIG. 5 is a plan view of a conventional cartridge, and FIG. 6 is a perspective view of the cartridge. In addition, in the symbols shown in the drawings, 1------------1--Cartridge 2--
−−−−−・−・−−−−One cartridge body 3−・−
・−・・−・−Opening 4−−−−−−−−1・・−Floppy disk 5−−
--------------Shutter 10-----
-----...-Magnetic head 11-...-1~-1--
Pad 12.13...--Magnetic layer 14------------- Floppy disk 1
6-...----1--Support 17--Magnetic particle coating layer 1
8-----・----1・----1 magnetic thin film 23・-m
------Magnetic paint application means 23c ---
−−−・−・−・Magnetic paint 34−・−−−−−−・・−
- One-rotation drum 38 - - - One - - This is an evaporation source (evaporation metal). Agent Patent Attorney Hiroshi Aisaka Figure 1 Figure 2 Figure 3 Dimensions

Claims (1)

[Claims] 1. A disc-shaped magnetic recording medium in which a magnetic particle coating layer formed by applying a magnetic paint and a magnetic thin film made essentially only of a magnetic material or a magnetic thin film with an intermediate layer interposed therebetween are sequentially laminated on a support.