JPH05298688A - Surface grinding tape for magnetic disk - Google Patents

Abstract

PURPOSE:To provide a surface grinding tape for a magnetic disk giving a smooth surface after grinding and capable of surely removing a fine ground layer when the surface of the magnetic layer of a flexible magnetic disk is smoothened. CONSTITUTION:When a grinding layer 11 consisting essentially of abrasive grains and a binder is formed on a substrate 9 to obtain a surface grinding tape 2 for a magnetic disk, an underlayer 10 having >=200W/m.K thermal conductivity is interposed between the substrate 9 and the grinding layer 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface polishing tape for a magnetic disk, and particularly when manufacturing a magnetic recording medium such as a flexible magnetic disk or a magnetic tape, smoothing the magnetic recording surface of the magnetic recording medium. The present invention relates to a surface polishing tape for magnetic disk used for intended surface polishing.

[0002]

2. Description of the Related Art Generally, in a flexible magnetic disk manufactured by providing a magnetic layer composed of magnetic powder and a binder on a flexible non-magnetic support, the magnetic property of the flexible magnetic disk is further improved. After the layer formation, the surface is polished in the circumferential direction. By performing such surface polishing treatment, the running of the flexible magnetic disk is stabilized,
The recording / reproducing spacing loss between the magnetic head and the magnetic disk can be significantly reduced, and as a result, good electromagnetic conversion characteristics can be obtained. Therefore, the development of ultra-smooth medium design technology for magnetic disks is strongly desired. In the method for polishing the surface of the flexible magnetic disk, a so-called polishing tape having a polishing layer composed of abrasive particles and a binder provided on a flexible support is rotated at high speed while being supported by an elastic roll (backup roll) or the like. It is generally performed by contacting the flexible magnetic disk. In the surface polishing of the flexible magnetic disk, it is important that the polishing processing speed is fast from the viewpoint of productivity, secondly that scratches and the like are not generated, and thirdly that polishing dust is not redeposited. Scratch induction is improved by improving the performance of the polishing tape. However, the attachment of polishing dust to the flexible magnetic disk causes a so-called missing error, and it is an important matter that the polishing dust does not reattach. Various studies have been made in the past as a measure for preventing the polishing dust from adhering to the surface of the flexible magnetic disk. That is, measures such as spraying cleaning air onto the surface of the flexible magnetic disk during rotary polishing, suction and dust removal on the surface of the flexible magnetic disk, and forced wiping with a cleaning tape made of a non-woven fabric are mentioned. However, the conventional measures are insufficient to completely remove the minute polishing dust, and it is difficult to obtain a flexible magnetic disk having excellent track quality. Furthermore, when a flexible magnetic disk made by the conventional method as described above is used for a long time, minute polishing debris that does not cause an error in the initial state peels off with the lapse of use time and accumulates on the magnetic head. However, it may be reattached to the flexible magnetic disk to induce an error or the like, and it is extremely difficult to obtain sufficient track quality reproducibility.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems. When the surface of a magnetic layer of a flexible magnetic disk is polished smoothly, the surface after polishing is smooth and fine polishing dust is surely produced. To provide a surface polishing tape for a magnetic disk capable of producing a flexible magnetic disk that is finished in a removed state, resulting in less occurrence of missing errors, excellent track quality, and excellent reproducibility. is there.

[0004]

In order to solve the above-mentioned problems, the present invention focused on the components of the polishing dust and analyzed the components, and found that the components were the same as those in the magnetic layer.
That is, it was found that it contains magnetic powder and a binder, and the residual amount of these polishing debris is the softness of the magnetic layer, that is,
It was found that it depends on the glass transition temperature (Tg) of the magnetic layer. That is, the surface temperature of the flexible magnetic disk to be polished during polishing momentarily rises to a considerably high temperature.
For example, as shown in FIG. 2, the flexible magnetic disk 1 to be polished rotates in the direction of arrow 7, and the polishing tape 2 supported by the backup roll 4 above it moves in the direction of arrow 8 and The surface of a flexible magnetic disk having a diameter of 3.5 inches under the processing conditions shown in Table 1 in a flexible magnetic disk polishing apparatus having a mechanism of pressing the flexible magnetic disk 1 against the polishing tape 2 with the air blown from the slit air nozzle 5 When the temperature during polishing was measured on the surface immediately after the surface to be polished with a radiation thermometer, it is considered that the temperature near the surface to be polished is as high as 50 ° C. or higher. However, since the glass transition temperature of the magnetic layer of the flexible magnetic disk is usually designed in the range of room temperature to about 50 ° C., the surface temperature to be polished of the flexible magnetic disk during polishing exceeds the glass transition temperature of the magnetic layer. It was found that the polishing dust containing the binder component reattached firmly to the surface of the flexible magnetic disk. From the above, as a means for solving the above-mentioned problems, performing the surface polishing treatment at a temperature at which the magnetic layer of the flexible magnetic disk is lower than the glass transition temperature of the magnetic layer eliminates the above-mentioned problems and improves the surface quality. It has been found that a flexible magnetic disk can be obtained. Therefore, in the surface polishing for smoothing the surface of the flexible magnetic disk, the surface of the flexible magnetic disk is polished so that the temperature environment of the magnetic layer is lower than the glass transition temperature (Tg) of the magnetic layer. The thermal conductivity between the support and the polishing layer is 20.
By forming an underlayer of 0 W / (m · K) or more,
A surface polishing tape for a magnetic disk, which is characterized in that frictional heat generated during polishing is transferred to the outside to prevent a temperature rise on the surface of the flexible magnetic disk.

[0005]

[Table 1]

That is, the present invention provides a magnetic disk polishing tape comprising a support and a polishing layer formed on the support, the polishing layer comprising abrasive particles and a binder and the like. A surface-polishing tape for a magnetic disk, comprising an underlayer having a thermal conductivity of 200 W / (m · K) or more between the polishing layers.

[0007]

Using a polishing tape comprising a support obtained by the present invention, a polishing layer and an underlayer having a thermal conductivity of 200 W / (m · K) or more, in addition, a backup roll supporting the polishing tape from the rear side is cooled. By polishing the surface of the flexible magnetic disk in this state, the transfer of frictional heat generated during polishing is promoted, so the temperature rise near the surface to be polished can be reduced, and the magnetic layer of the flexible magnetic disk is kept above the glass transition temperature. Can be polished under low temperature conditions. As a result, it is possible to prevent the reattachment of polishing dust to the surface of the flexible magnetic disk.

[0008]

Examples As the support which can be used in the present invention, there are long films such as polyethylene terephthalate (PET) and polyimide, and any of them may be used. The abrasive particles may be fine powder having a Mohs hardness of 6 or more, and examples thereof include fused alumina, silicon carbide, chromium oxide, α-iron oxide, diamond, silicon oxide, and titanium oxide. The average particle size of the fine powder is 0.01 μm to 10 μm.
m, preferably 0.3 μm to 3 μm. As the binder, a commercially available resin can be used. For example, as the binder used in the present invention, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, epoxy resin, phenoxy resin, vinyl chloride-propion trivinyl copolymer, vinyl chloride-acrylic acid ester copolymer Examples thereof include polymer, vinyl chloride-vinyl acetate-maleic acid copolymer, polyvinyl butyral resin, acrylonitrile-butadiene copolymer, polyurethane resin and the like. As the substance having a thermal conductivity of 200 / W (m · K) or more used in the present invention, gold,
Metals such as silver, copper and aluminum can be mentioned.

As a base layer, polyethylene terephthalate (P) having a thickness of 50 μm, which is a support, is formed by a vacuum deposition method.
ET) with a copper coating. The film forming conditions are a film conveying speed of 30 m / min and an ultimate pressure of 8 × 1.
It was set to 0 ^-5 Pa. The thickness of the underlayer obtained at that time is 1 μm
Is.

As the polishing layer, fused alumina (average particle size 0.5 μm) 80 parts by weight Polyurethane resin (Tg 25 ° C.) 6 parts by weight (solid content) Polyvinyl chloride (Tg 79 ° C.) 14 parts by weight (solid content) Methyl ethyl ketone / A raw material having a composition of 90 parts by weight / 90 parts by weight of toluene was kneaded in a ball mill for 30 hours, and then an isocyanate compound (Coronate L manufactured by Nippon Polyurethane Company) was used.
4 parts by weight was added and the mixture was kneaded for 1 hour to obtain a coating material. This is coated and dried on the above-mentioned underlayer so that the thickness of the dried polishing layer is 15 μm, and 100 is applied to a core having an inner diameter of 6 inches
m winding, this was cured at 65 ° C. for 72 hours.
After curing, slit into 1 inch width, as shown in Fig. 1,
A polishing tape having a base of about 50 μm polyethylene terephthalate (PET), a base layer of about 1 μm copper film, and a polishing layer of about 15 μm coating film was obtained.

[0011]

[Comparative Example] When producing an abrasive tape by the method of the example,
An abrasive tape prepared in the same manner as in Example except that only the abrasive layer was formed on the support.

Each of the polishing tapes obtained in the above Examples and Comparative Examples was mounted in a flexible magnetic disk polishing apparatus having the mechanism shown in FIG. 2, and surface polishing was performed under the processing conditions shown in Table 1 to obtain samples. 100 sheets were prepared. At that time, the backup roll was cooled to 5 ° C. The flexible magnetic disk prototyped using the polishing tapes produced in the above-mentioned Examples and Comparative Examples was measured for track quality according to the specifications shown in Table 2 to obtain the yield. Here, the signal level of the error determination standard is the average signal amplitude of the recording track is 1
This is a criterion for determining an error when it is set to 00%. The results of the above yields are shown in Table 3.

[0013]

[Table 2]

[0014]

[Table 3]

Next, all the samples that passed the above-mentioned track quality measurement were mounted on a commercially available 3.5-inch micro-floppy disk drive, subjected to random seek for 12 hours at room temperature and normal humidity, and then again in the same manner. The track quality was measured and the yield was calculated. Table 3 shows the results of repeating the above-mentioned repetitions a total of 5 times. The yield at this time was 100% based on the total number of samples that passed the previous track quality measurement. As can be seen from the results of Table 3 above, the track quality and data reproducibility of the flexible magnetic disk after surface polishing are improved by using the surface polishing tape for magnetic disks of the present invention. It should be noted that the same effect was obtained even when the underlayer was manufactured by a method other than the vacuum vapor deposition method and another method by which the required film thickness was obtained. Therefore, the present invention is not limited to the conditions for forming the underlayer shown in the examples.

[0016]

As described above, by using the surface polishing tape for a magnetic disk according to the present invention, it is possible to obtain a flexible magnetic disk having excellent track quality and reproducibility.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a sectional configuration of a surface polishing tape for a magnetic disk according to an embodiment of the present invention.

FIG. 2 is an external perspective view showing an outline of a surface polishing apparatus for a flexible magnetic disk used in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 1 Flexible Magnetic Disk 2 Polishing Tape 3 Guide Roll 4 Backup Roll 5 Slit Air Nozzle 6 Guide Roll 7 Arrow 8 Arrow 9 Support 10 Underlayer 11 Polishing Layer

Claims (1)

[Claims] 1. A magnetic tape polishing tape comprising a support and a polishing layer formed on the support, the polishing layer comprising abrasive particles, a binder and the like. A surface polishing tape for a magnetic disk, which has an underlayer having a thermal conductivity of 200 W / (m · K) or more between them.