JP2515154B2 - Flexible magnetic disk - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a flexible magnetic disk, and more particularly to a flexible magnetic disk which can be loaded on a wording and reading device without eccentricity.

[Prior Art and its Problems] Conventionally, a flexible magnetic disk sheet is housed in a jacket, and a sheet positioning member of a writing / reading device is engaged with a central circular hole provided in both the jacket and the sheet, and is rotated. Magnetic recording on the sheet,
Alternatively, magnetic reproduction from a sheet is known.
In this type of magnetic disc, the sheets are stored in the jacket with some allowance, so when storing, handling or carrying, the sheet inside shifts to a biased position in the jacket, and when the disc is loaded into the device, The circular hole at the center of the sheet may be eccentric with respect to the position of the positioning member (collet) of the apparatus, and the sheet may be held at the eccentric position during positioning.

FIGS. 1A and 1B show a flexible magnetic sheet of this type, in which a circular jacket 1 having a circular opening 1a in the center is formed into a circular shape in which the peripheral edge of a central circular hole 2a is exposed in the central circular opening 1a. The flexible magnetic sheet 2 is stored rotatably.

When the flexible magnetic disk is loaded in the writing and reading device, the rotating portion 3 of the positioning member is applied from below the sheet 2 as shown in FIG. 2, and the collet 4 is lowered from above to form a circular concave portion of the rotating portion 3. Press into 3a.
At this time, the peripheral edge of the central circular hole 2a of the sheet 2 does not always coincide with the position of the circular recess 3a of the rotating portion 3,
Since it is often displaced, if the collet 4 is lowered as it is, a part of the peripheral edge of the circular hole 2a of the sheet 2 is clamped between the collet 4 and the recess 3a of the rotating part 3 as shown in FIG. Will rotate. The magnetic disk sheet 2 must be prevented from being held in such a position because writing and reading cannot be performed correctly unless the center is properly rotated so as to coincide with the center axis of rotation. Also,
If the sheet 2 is held and rotated in such a state, the flatness of the sheet 2 is impaired, and there is also a problem of rattling at the time of rotation. When the collet 4 is lowered and the sheet 1 is sandwiched, in order for the sheet 1 to be properly loaded not as shown in FIG. 3 but as shown in FIG. 4, the peripheral edge of the central circular hole of the sheet has an appropriate hardness, In addition, it is necessary that the friction coefficient (μ) between the sheet 1 and the collet 4 and the rotating portion 3 is small.

As one measure for this purpose, JP-A-57-1134
22 discloses a method of reducing a friction coefficient by providing a protective layer containing a polyolefin resin and a fatty acid ester, which are polymerizable by ultraviolet rays, at a portion of the flexible magnetic disk which is in contact with the sheet positioning member on the periphery of the central circular hole. ing.

However, simply providing a protective layer made of an ultraviolet curable resin causes a smooth surface, or due to the softness of the resin, when the flexible magnetic disks are stacked in a state where the protective layers are in contact with each other in the manufacturing process, It may adhere between the protective layers of each other and cause blocking.

Further, in a high temperature and high humidity, when the clamped state is kept for a long time in the Froppy disk drive device, the protective layer may adhere to the rotating part or the collet.

In order to prevent such a situation, a method of hardening a resin or mixing a filler is disclosed in Japanese Patent Laid-Open No.
-234273.

However, when the resin is hardened, the adhesion to the magnetic layer is reduced, and the protective layer may fall off during use. Further, when a filler is used, the filler often absorbs ultraviolet rays and the resin may not be sufficiently cured.

A method of using an epoxy resin, a synthetic rubber or the like for a protective coating of an ultraviolet curable resin is also disclosed in Japanese Utility Model Publication No. 57-28298, but it is still difficult to achieve both adhesion and prevention of adhesion between protective layers. It was

Further, the single-layer protective layer of the ultraviolet curable resin has a drawback that the surface thereof is likely to be scratched as the number of times of attachment / detachment to / from the floppy disk drive is increased.

Further, in recent years, the floppy disk has been required to have a fashionability, and, for example, there is a tendency that a jacket is colored. There has also been a strong demand for coloring the protective layer provided around the central circular hole of the flexible magnetic disk.

However, when a pigment is incorporated into a protective layer mainly composed of an ultraviolet curable resin for coloring, the pigment absorbs ultraviolet rays, so that the hardness is not sufficient and the above adhesion problem occurs.

[Problems to be solved by the invention]

The present invention has been made in view of the above-mentioned problems of the prior art, and has a small friction coefficient with a positioning member, is properly loaded into a drive, and is adhered to each other even when stacked, and particularly under various temperature and humidity conditions. It is an object of the present invention to provide a flexible magnetic disk which is rich in versatility and does not adhere to a rotating part or a collet even if a clamped state continues for a long time in a drive.

[Means for solving problems]

The object of the present invention is to provide a flexible magnetic disk having a protective layer on the periphery of the central circular hole, wherein the protective layer is partially formed on the peripheral edge of the central circular hole, and is a drying oil, a semi-drying oil, or a drying oil. At least one of a modified resin and a semi-drying oil-modified resin, and a lower layer mainly composed of pigment particles, and an upper layer mainly composed of a resin obtained by irradiating a radiation-polymerizable compound with radiation to cure the resin. It is achieved by a flexible magnetic disk featuring.

The lower layer of the protective layer provided around the central circular hole of the flexible magnetic disk of the present invention is a vehicle mainly composed of at least one of a drying oil, a semi-drying oil, a drying oil-modified resin and a semi-drying oil-modified resin. A composition in which pigment particles are dispersed is applied, dried and applied, and a drying oil,
Since there is at least one of semi-drying oil, drying oil-modified resin, and semi-drying oil-modified resin, it dries in a relatively short time after application and is left in the air to solidify gradually due to the action of oxygen To form a simple film.

Further, on the lower layer is protected by an upper layer mainly composed of a resin cured by irradiating a radiation-polymerizable compound with radiation, and the protective layer is partially formed, so that The contact points are limited and there is almost no adhesion between the protective layers even when the flexible magnetic disks are stacked and placed.

In the flexible magnetic disk of the present invention, not only the protective layer provided on the peripheral edge of the central circular hole has high coating strength but also the protective layer is partially provided, so that the sliding property of the protective layer can be improved. The coefficient of friction with the positioning member of the drive is small, so that there is no eccentricity when the flexible magnetic disk is loaded in the drive device.

The lower layer is a composition mainly composed of at least one of a drying oil, a semi-drying oil, a drying oil-modified resin and a semi-drying oil-modified resin and a pigment particle, which is dried in a relatively short time after application and is dried by air. When left inside, it gradually solidifies due to the action of oxygen to form a tough film and also has good adhesion to the magnetic layer and the upper layer of the flexible magnetic disk, and also has the effect of increasing the adhesion of the protective layer. Therefore, the adhesion with the upper layer is enhanced, and the protective layer does not drop off during use to increase drop-out.

Furthermore, because the lower layer acts as a cushion, it is more difficult than the case where the protective layer is made of a single layer of resin to prevent the protective layers from sticking to each other even if the flexible magnetic disks are stacked. Also, scratches are less likely to occur.

Another advantage of the flexible magnetic disk of the present invention is that by selecting various colored particles as the pigment particles of the lower layer of the protective layer, it is possible to impart fashionability, and further, how to determine the arrangement pattern of the protective layer. It is possible to give distinctiveness.

Further, since the upper layer does not have a substance such as a filler that absorbs ultraviolet rays, it is possible to sufficiently proceed the curing of the ultraviolet curable compound, which has a large surface hardness, is hard to be scratched, and has a small friction coefficient. It is believed that this facilitates the many advantages of the flexible magnetic disk of the present invention described above, which does not have a protective layer that is hard to adhere.

In the flexible magnetic disk of the present invention,
A protective layer forming region 11 is annularly formed on the periphery of the central circular hole 10a of the flexible magnetic sheet 10 shown in the plan view of the figure.

Then, as is clear from the partial view of the flexible magnetic sheet of FIG. 6, in the protective layer forming region 11, for example,
The protective layer 12 is partially provided in a radial stripe pattern as shown in FIG. 6 (A), concentric stripe patterns as in (B), and a checkerboard pattern as in (C).

The protective layer forming region 11 is preferably formed with a width of 1 to 8 mm from the circular hole peripheral edge 10a.

Further, the area ratio of the protective layer 12 in the protective layer forming region 11 is preferably in the range of 20 to 90%.

The total thickness of the protective layer 12 is 1 to 150 μm, preferably 2 to 50 μm.

If the total thickness of the protective layer 12 is too thin, it will be difficult to apply the protective layer 12 uniformly, and the hidden pay power will be reduced. If it is too thick, it takes time to dry, which is not desirable.

The thickness of the lower layer of the protective layer 12 is preferably 1 to 25 μm.

The upper layer of the protective layer 12 has a thickness of 1 to 25.
μm is desirable.

The protective layer 12 can be provided on the flexible magnetic sheet by various conventional coating means. Among them, various printing means are preferable because of high productivity.

For example, gravure printing, silk screen printing, flexographic printing, letterpress printing, dry offset printing, tampo printing can be used.

In addition, it is desirable that the protective layer 12 be provided on both front and back surfaces of the peripheral edge of the central circular hole.

After the coating of the upper layer of the protective layer 12 is completed, radiation is applied to polymerize and cure the radiation-polymerizable compound of the upper layer.

The radiation used at that time is low energy radiation such as ultraviolet rays, high energy radiation such as α rays, X rays,
An electron beam can be used. Of these, an ultraviolet ray generator is particularly preferable because it is simple.

When using ultraviolet rays as radiation, it is preferable to include an aromatic ketone as a photopolymerization initiator. Aromatic ketones include, but are not limited to, 254, 313, 36 that produce the emission line spectrum of mercury lamps that are commonly used as UV light sources.
Those having a relatively large absorption coefficient at a wavelength of 5 nm are preferred.

The compound having an unsaturated bond capable of being polymerized by radiation used for the upper layer of the protective layer of the present invention is a compound having at least one carbon-carbon unsaturated bond, and is an acryloyl group, an acrylamide group or an allyl group. A compound containing a group and the like, and further a vinyl compound, a compound containing an ether bond with a thiovinyl compound, and an unsaturated polyester, and specifically, acrylic acid alkyl ester which is a methyl acrylate and its homolog, styrene and its Examples include homologues such as α-methylstyrene and β-chlorostyrene, acrylonitrile, vinyl acetate, and vinyl propionate. Two or more unsaturated bonds may be present in the molecule. As an example of this compound, "Photosensitive Resin Data Collection", Sogo Chemical Laboratory Co., Ltd., published in December 1968, 23
The compounds listed on pages 5-236 are mentioned.

As the drying oil or the semi-drying oil which is the main component of the lower layer of the protective layer coated around the central circular hole of the flexible magnetic disk of the present invention, vegetable oil having an iodine value of 130 or more or its synthetic oil can be used.

Examples thereof include linseed oil, cinnamon oil, eno oil, soybean oil, dehydrated castor oil, rosin, maleated oil, styrenized oil, urethane oil and the like.

In addition, as a dry oil-modified resin, semi-dry oil-modified resin,
For example, modified alkyd resin, modified phenol resin, rosin ester, maleic acid resin and the like can be mentioned.

The amount of the drying oil, the semi-drying oil, the drying oil-modified resin or the semi-drying oil-modified resin in the composition of the lower layer is preferably in the range of 30 to 80% by weight based on the whole composition.

If the amount is too small, the viscosity becomes high and the printability is deteriorated, and if it is too large, the coloring effect of the pigment is deteriorated, which is not desirable.

As the pigment particles in the lower layer, various organic pigments and inorganic pigments can be used, and most of those conventionally used in the field of paints and printing inks can be used.

Examples of organic pigments include Hansa Yellow, Pyrazolone Orange, Brilliant Huast Scarlett, Pyrazolone Red B, Resole Red R, Lake Red C, Brilliant Carmine 6B, Rhodamine 6G Lake, and Phthalocyanine pigments.

Examples of the inorganic pigments include titanium oxide, zinc oxide, barium sulfate, yellow lead, carbon black, molybdenum red, red iron oxide, chromium oxide, alumina, navy blue, and ultramarine blue.

The particle size of the pigment particles in the present invention is generally desirably 0.01 to 5 μm.

If the particle size is too large, the hiding power will be reduced, and if it is too small, the dispersion will be insufficient, causing a problem.

Further, the content of the pigment particles in the composition is 10
It is desirable to be 60 to 60% by weight.

By incorporating matting agent particles in the upper layer or the lower layer of the protective layer of the flexible magnetic disk of the present invention, there is an advantage that the friction coefficient between the protective layer and the positioning member of the drive can be further reduced.

The matting agent particles are inorganic or organic particles added to roughen the surface of the protective layer.
As the inorganic fine particles, zinc oxide, nickel oxide, titanium oxide, silicon oxide, barium sulfate, talc, kaolin,
Chromium oxide, cadmium sulfide, goethite, alumina,
Examples include calcium carbonate. Of these, silicon oxide and alumina are particularly preferable. By treating the surface of these inorganic fine particles with an organic substance, the friction coefficient can be reduced. As the organic fine particles, thermoplastic polymer powder, for example, acetyl cellulose, polyethylene, polypropylene, polystyrene, thermoplastic polyester,
Examples thereof include polyamide, polyacrylonitrile, and polyacetal resin powders, and thermosetting polymer powders such as phenol resin, urea resin, triazine resin, melamine resin, epoxy resin, furan resin, and acrolein resin. These are desirably insoluble in the radiation-curable compound or organic solvent used together. Of these, urea resins and furan resins are particularly preferred. The particle diameter of these fine particles has an optimum value which varies depending on the thickness of the protective layer when dispersed and applied in a resin. For example, in the case of a protective layer of 5 μm, the average particle diameter is 0.1 to 10 μm, Preferably 1-10 μm, more preferably 2-8 μm
m. As the thickness of the protective layer increases, the lower and upper limits of the particle size also increase. The thickness of the protective layer after curing is preferably 1 to 30 μm.

 A lubricant may be contained in the upper layer.

The matting agent particles are contained in the upper layer composition in an amount of 1 to 50% by weight, preferably 5 to 30% by weight, more preferably 10 to 25% by weight.

〔The invention's effect〕

Drying oil, a semi-drying oil, a drying oil-modified resin and a semi-drying oil-modified resin, and a lower layer comprising a composition mainly composed of pigment particles and a radiation-polymerizable compound on the lower layer to be cured by irradiation. By partially providing the protective layer consisting of the upper two layers of the resin-based composition on the peripheral edge of the central circular hole, the coefficient of friction with the positioning member is small, and the protective layer falls off during use and drops. It is possible to obtain a flexible magnetic disk that does not increase the out and does not cause the protective layers to adhere to each other even if they are stacked.

Further, the flexible magnetic disk of the present invention can be made to have a fashionability and a distinctiveness.

The novel effects of the present invention will be clarified by the following examples and comparative examples.

[Example-1] The protective layer 12 of the present invention was provided in the protective layer forming regions 11 on both the front and back sides at the periphery of the central circular hole 10a of the flexible magnetic disk sheet 10 of Fig. 5 as follows.

(Coating liquid for lower layer composition of protective layer) 100 parts by weight of linseed oil varnish Titanium oxide (average particle diameter 4 μm) 40 parts by weight (Coating liquid for upper layer composition of protective layer) Polyurethane acrylate (M manufactured by Toagosei Kagaku Co., Ltd.) −
1100) 100 parts by weight SiO ₂ powder (average particle diameter 4 μm) 20 parts by weight benzoin ethyl ether 5 parts by weight butyl stearate 5 parts by weight Coating for the lower layer composition on one surface of the peripheral edge of the central circular hole of the flexible magnetic disk sheet The liquid was printed by a relief printing method with a width of 3 mm and a radial stripe pattern as shown in FIG. 6 (A) with an interval of 3 mm, and immediately thereafter, a layer thickness was applied by the same relief printing method as the coating solution for the upper layer composition. Was printed to be 4 μm.

Then, ultraviolet rays were irradiated from a high pressure mercury lamp at an intensity of 80 W / cm ² to polymerize and cure the upper layer composition to form a protective layer.

A protective layer was formed on the other surface of the central circular hole periphery of the flexible magnetic disk under the same conditions, and protective layers were provided on both surfaces of the central circular hole periphery.

[Example-2] The above-mentioned flexible magnetic disk provided with a protective layer on both sides of the central circular hole periphery under the same conditions as in Example-1, except that the coating composition for the upper layer composition of the protective layer was the following composition. Created.

(Coating liquid for upper layer composition of protective layer) Polyurethane acrylate (M- manufactured by Toagosei Co., Ltd.)
1100) 100 parts by weight trimethylolpropane triacrylate 30 parts by weight benzoin ethyl ether 5 parts by weight butyl stearate 5 parts by weight [Comparative Example-1] Protection consisting only of the upper layer composition of Example-1 on both sides of the central circular hole. A flexible magnetic disk was prepared in which the layers were formed under the same conditions as in Example-1.

[Comparative Example-2] A flexible magnetic disk was prepared in which protective layers made of only the upper layer composition of Example-2 were formed on both sides of the central circular hole under the same conditions as in Example-2.

[Comparative Example-3] A protective layer was not provided around the central circular hole of the flexible magnetic disk.

The flexible magnetic disk obtained in the above example and the comparative example was measured for the friction coefficient with the upper positioning member of the drive, and the loading test for the disk drive was performed at 25 ° C.
The results obtained under the conditions of% RH are shown in the table.

The coefficient of friction was measured by rubbing the positioning member (collet) on the magnetic sheet at a feed rate of 0.8 mm / sec. And applying an additional load of 70 g weight. Positioning member (rotating part)
Similarly, the coefficient of friction between and was measured.

The drives used for the loading test on the disk drive were YD-280 and 380 manufactured by Y-E Data, and Matsushita Tsuko.
JA751 and 561, Mitsubishi Electric Corporation M-2894 and 4853.

The results are shown by "○" when no failure occurred in all drives after repeated loading 10 times and "x" when one or more drives failed.

Also, the table shows the adhesion rate (%) to the rotating part of the disk drive under the condition of 40 ° C and 80% RH. As a drive, YD-480 manufactured by YE Data Co., Ltd. was used, and adhesion with the rotating part after continuous 12h clamping was observed. The results are shown in Table 1. Also, stacking 10 sheets 1k
The adhesion ratio between the disks when g is applied is also shown in the table.

Comparative Examples 1 and 2 have almost the same level of vest as the Examples of the present invention, but in Comparative Example, adhesion to the rotating portion of the disk drive occurs. Further, when a test of stacking ten flexible magnetic disk sheets at 40 ° C. and 80% RH was carried out, the occurrence of adhesion was found in Comparative Example 1.

Next, using a YD-380 manufactured by Y-E Data Co., Ltd., at 25 ° C. and 50% RH, the protective layer was removed and scratched after 50,000 cycles of repeated desorption tests, and 180 ° using Permacel double-sided tape p941. Table 2 shows the results of the measurement of adhesion force by peeling.

[Brief description of drawings]

FIG. 1A is a plan view showing an example of a flexible magnetic disk, FIG. 1B is its sectional view, FIG. 2 is a partial sectional view showing a state in which the flexible magnetic disk is mounted on the positioning member of the apparatus, and FIG. 3 is the same. FIG. 4 is a partial sectional view showing a state in which the sheet is held eccentrically, FIG. 4 is a partial sectional view showing a state in which the sheet is correctly positioned, and FIG. 5 is a sheet portion of one embodiment of the present invention. FIG. 6 is a partial view showing the periphery of the central circular hole of the flexible magnetic sheet. 1 ... Jacket, 1a ... Jacket opening 2 ... Magnetic sheet, 2a ... Central circular hole 3 ... Positioning member (rotating part) 3a ... Circular recess 4 ... Positioning member (collet) 10 ... Magnetic sheet, 10a: central circular hole 11: protective layer forming area 12: protective layer

Claims (1)

(57) [Claims] 1. A flexible magnetic disk having a protective layer on the periphery of a central circular hole, wherein the protective layer is partially formed on the peripheral edge of the central circular hole, and is a drying oil, a semi-drying oil or a drying oil modified resin. And a lower layer mainly composed of at least one of semi-drying oil-modified resin and pigment particles, and an upper layer mainly composed of a resin which is cured by irradiating a radiation-polymerizable compound with radiation. Flexible magnetic disk.