JPS6337823A - Flexible magnetic disk and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a disk with less flaw and track deviation by radiating a radiant ray only to a center hole circumference part so as to improve the film coating strength of the part more than that of a recording face in the coating film made of a magnetic paint including a material such as monomer capable of being polymerized by a radiant-ray. CONSTITUTION:A magnetic paint C is obtained by adding a radiant ray curing binder B in addition to a flexible magnetic disk use magnetic paint A as a basic paint. The magnetic paint C is applied to both sides of a PET film, the result is drived in a drying furnace 6 and cured to form a magnetic sheet. Then the sheet is punched into a desired size to radiate a radiant ray to a part wider than the center hole part to cure it further, the sheet is punched in a form of doughnut to form a flexible magnetic disk 1. Thus, the paint process of the paint is simple and the flatness is excellent, then the track accuracy and size accuracy are excellent in loading the disk 1 and a positioning member 2 and a flaw is hardly given the center hole circumferential part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of application in the FI industry) The present inventor relates to the improvement of flexible magnetic disks. This article is about flexible magnetic disks that are hard to break.

(Binmai's technology) A flexible magnetic disk sort is stored in a jacket, and the sheet positioning part (collet) of the writing/reading device is engaged with the center hole provided in the center of the notebook, and the sheet positioning part (collet) of the writing/reading device is rotated. There are known devices that magnetically record on or magnetically reproduce from a notebook.

In this type of magnetic disk, the sheet is stored in the jacket with some margin, so the sheet is often stored in a lopsided position in the jacket, but when loading the disk into the device, the sorter rotates and The center hole of the sheet is located on the inclined side of the positioning member (collet) of the device and its position is corrected, and in that state it is held in place by being held between the turn tape and the flange of the collet. Therefore, if it is repeatedly attached and detached, scratches tend to form around the center hole. To prevent this, there are examples of improvements such as pasting a ring note on the periphery of the center hole to reinforce it (US Patent No. 4052750) or applying radiation-cured resin to the periphery (JP-A-Sho, 1). 7 1
No. 13422, No. 60-80132) (Problems to be Solved by the Invention) Conventionally, in both cases, the adhesive was pasted or coated afterwards, making the process complicated and increasing costs. In addition, in the case of attaching a reinforcing ring and applying a reinforcing material, if the thickness exceeds the required thickness, off-track is likely to occur during recording. Therefore, we conducted extensive research to see if it could be improved without changing the thickness, and as a result, we found that
The present inventors have discovered a method in which the reinforcing effect can be exhibited only by irradiation with radiation without pasting or applying it in a ring shape, leading to the present invention.

(Means for Solving the Problems) In the present invention, the paint used for the magnetic sheet is based on the magnetic paint (A) for flexible magnetic disks, and in addition, some radiation-curing binders are used (at 50°C, 72H).
Then, a magnetic sheet is produced.

The notebook is then punched in the center before being punched out to the required dimensions. Or, after punching, make it into a ring-shaped part.
It may be irradiated after being inserted into the jacket.

The radiation mentioned here includes low-energy radiation (ultraviolet rays) and high-energy radiation (α-rays, X-rays, electron beams, etc.), but ultraviolet rays desirable.

The magnetic paint (A) contains magnetic powder (rF'zO3, Co-containing rF'20s + meta/l/p4, etc.), binder (PVC/acetate-picopolymer, PVC/vinyl acetate/polyvinyl alcohol terpolymer) , PVC/vinylidene chloride copolymer.

urethane elastomers, other thermosetting binders, etc.), additives (dispersants, lubricants, etc.).

abrasives, hardeners, antistatic agents, etc.), solvents (MEK.

MIBK, toluene, cyclohexanone, etc.)
Next, a mixed liquid (B
) to prepare the final magnetic paint (C).

(Function) The present invention has a simple paint application process and good flatness, so when the flexible magnetic disk and the positioning member (collet) are loaded, the tracking accuracy is improved.

It is possible to provide a flexible magnetic disk that has no problems in terms of dimensional stability and is less likely to be damaged at the periphery of a center hole.

(Examples) Specific examples of the present invention are as follows.

Actual example 1゜(A Sou) Magnetic powder (r p4.o,, Hc=3000e,)
200! Partial dispersion (shi/chin)
6 smoothing (TDS) 1° abrasive (Af203) IQ carbon black 18 urethane prepolymer (N
CO content 13.3% MEK/toluene 30% liquid) 37MEK
'450 toluene
250 (Liquid B) Penzylmethyltakel 1 (Ci) = (
A liquid) + (B liquid) The above C liquid was coated with a reverse coater or a gravure coater at 75%.
Both sides of the μm PET film are coated to a dry thickness of 2.5 μm each. After drying and calendering, it was wound up and heat-cured at 500C for 72 hours to produce a magnetic sheet. The sheet can be punched out to the required size (5" or 8") as it is, and after burnishing (surface polishing), it can be inserted into a flexible magnetic disk, but in addition, radiation ( irradiate with ultraviolet rays),
Further: harden with. If this happens and radial hardening occurs all the way to the recording surface, it will cause problems such as a drop in output due to head wear when recording and reproducing over a long period of time, so it is limited to the periphery of the center hole.

The radiation source was a metal halide lung (120 W/cm) and was treated at 10 crn for 24 seconds. The flexible magnetic disk produced in this way is used in a disk drive (
The collet was loaded into YE Data Co., Ltd. YD-274) and the occurrence of scratches caused by the collet and the presence or absence of track deviation were confirmed, and the results are summarized in Table 1.

Example 2 Magnetic powder (contains co-F-203°□.: 600 oe) 20° parts by weight PVC/vinyl acetate/polyvinyl alcohol trig combination (UCC?f:VAGH) 49 Urethane elastomer with Tuboran #2301) 52°5 Dispersing agent (lecithin) 4 Lubricating agent (TDS)
10 urethane prepolymer (NCO13
,3%.

MEK/) Chef 30% liquid) 35 MBK 500 Toluene 300 Epoxy acrylate (Cemerox Super Y-860-2) Penzyl Ethyl Takele 1 Using the above paint in the same manner as in Example 1, flexin pull magnetic A sheet was prepared and the periphery of the center hole was irradiated with radiation for 14 hours.
A flexible magnetic disk was fabricated in seconds, loaded into a disk drive, and tested.

Example 3゜Actual flow example 2. In the above, the radiation-curing resin was replaced with urethane acrylate (Cemerok Super Y-860-1), and a flexible magnetic sort was produced in the same manner.
The radiation irradiation time was 30 seconds.

Example 4゜Example 1. In this example, a flexible magnetic sheet was prepared by replacing the radiation-curing resin with epoxy acrylate (Semerok Super Y-860-2), and the radiation irradiation time was 14 seconds.

Comparative example 1゜Example 1. A flexible/pull magnetic disk was prepared by applying only liquid A and curing with heat, and was used for testing. This is the same as the flexible magnetic disk before the improvement.

Comparative example 2゜Comparative example 1. A reinforcing ring sheet is attached to the periphery of the center hole of a flexible magnetic disk.

Comparative example 3゜Example 2. In, radiation-curable resin (epoxy acrylate) and photopolymerization initiator (penzyl ethyltakel)
A flexible 7-pull magnetic disk was produced after coating with the liquid except for the above and heat curing.

The above Examples and Comparative Examples Example 1. Each test was performed by loading the disc drive in the same manner as above.

As shown in Table 1, in the case of the example, compared to the comparative example, when the disk drive was loaded and tested, it was confirmed that there were no scratches caused by the collet and no trunk displacement occurred even during certify.

Table 1 (Effects of the Invention) The thickness of the flexible magnetic disk according to the present invention does not change, and the periphery of the setter hole of the flexible magnetic disk is particularly strengthened due to the synergistic effect of heat curing and radiation (ultraviolet) curing. Therefore, the conventional drawbacks of scratches and track misalignment are greatly improved0

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing an embodiment of the present invention in which the tray is normally loaded. Fig. 2 is a schematic diagram of the hot air drying process during painting, Fig. 3 is a schematic diagram of the thermosetting chamber, and Fig. 4 is a schematic diagram of the radiation (ultraviolet ray) curing process for the periphery of the center hole. Fifth
The figure is an external view of a notebook punched to the specified dimensions using a punching machine. Figure 6 shows the periphery of the center hole after radiation hardening of the punched flexible magnetic plate. 1...Flexible/Pull magnetic/-To 2...Collet 3/Kranobu (turntable) 4...Ultraviolet @ hardened rim 5...Center hole 6...-Drying oven 7 Thermosetting chamber 8... Ultraviolet lamp patent applicant Columbia Magne Products Co., Ltd.'
Q-i", Puff No. 151 1i2 Fig.", r l'91

Claims (1)

[Claims] A coating film is made of a magnetic paint containing a monomer or oligomer that can be polymerized by radiation, and by irradiating only the periphery of the center hole with radiation, the strength of the coating film in this area is made higher than that on the recording surface. A flexible magnetic disk and a method for manufacturing the same, characterized by: