JPH04358380A - Magnetic disk cartridge - Google Patents

Abstract

PURPOSE:To exhibit cleaning effect by providing a lifter between a hard case and a linear for cleaning provided on the inside of the hard case and specifying the physical quantity of the lifter. CONSTITUTION:This cartridge is composed of liners 3A, 3B for cleaning provided on the inside of the hard case capable of housing a magnetic disk rotatably, the hard case, the lifter 7 provided between the liners 3A, 3B and the magnetic disk 6. At this time, the lifter 7 consists of a high polymer film having 50-200mum thickness, 10-100% repture elongation and 150-1000kg/mm<2> Young's modulus, and thermoelasticity recovery factor is defined to be >=50%. Thus, the cleaning effect is not reduced and a stable and low soft error ratio is attained even when the device is exposed to the environmental condition of high temperature.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk cartridge equipped with an improved lifter for use in magnetic disk cartridges.

More specifically, in a hard case containing a magnetic disk and lined with a liner, the magnetic disk having the liner and a specific magnetic recording film is elasticized by a lifter having a specific thermoelastic recovery rate and other characteristics. The present invention relates to a magnetic disk cartridge that makes it possible to write signals to and read signals from a magnetic disk with high reliability under a wide range of environmental conditions.

[0003] The above-mentioned effect of improving reliability is particularly noticeable in a magnetic disk cartridge containing a magnetic disk having a high linear recording density. Further, in order to improve the environmental resistance of the magnetic disk cartridge, polyethylene naphthalate film can be preferably used as the non-magnetic support in the magnetic disk instead of polyethylene terephthalate film.

0004

[Prior Art] 3-inch or 3-inch media with high information recording density
．． For 5-inch diameter floppy disks, an automatic shutter mechanism is installed in the opening of the disk cartridge into which the head for recording/playing information is inserted, in order to prevent dust, fingerprints, etc. from adhering to the disk or from mechanical damage. A hard case is used. FIG. 1 shows the structure of a 3.5-inch floppy disk as an example, and shows the structure of a 3.5-inch floppy disk as an example. Magnetic disks 7 and 6, to which a metal hub 4 that enables rotation from the drive side is attached with adhesive, are assembled in a hard case consisting of a side 0 side). Liners 3A and 3B for cleaning are interposed between the magnetic disk 6 and the upper and lower shells 1 and 8, and the elasticity of the lifter 7 pushes the liners against the surface of the magnetic disk (
(elastic contact) to clean the surface of the magnetic disk.

When installing the magnetic disk cartridge into the drive, the shutter 9 opens and the head insertion slot 1 opens.
When the head is inserted into 1A and 11B and removed from the drive, the shutter spring 10 closes the shutter 9.
It has a mechanism that closes automatically.

Recent floppy disks are required to have high reliability under various harsh conditions, such as temperature, humidity, and dust, and for this reason, reducing soft errors has become an important issue. One of the causes of soft errors is dust that adheres to the magnetic disk, and as the disk rotates, the liner and disk come into appropriate contact, and the dust on the disk is efficiently removed.

When using a hard case of 3.5 inches or the like, a method is generally used in which the liner is forcibly brought into elastic contact with the disk surface using a lifter as shown in FIG. This lifter is often made of a polyethylene terephthalate (polyester containing polyethylene terephthalate as the main component) film having a thickness of about 75 μm. One end of the lifter is fixed (fixed) to the hard case with an adhesive 74 or the like, and the other end is bent at an angle (α) to serve as a free end (71) and brought into elastic contact with the liner. This bending angle (α) is 15°~
45° is used, and the size of the free end 71 is approximately 2
A size of about 0 mm x 20 mm is used.

The function of this lifter is to remove foreign matter generated on the surface of the magnetic disk. If there were no lifter, the liner would not come into elastic contact with the magnetic disk, making it impossible to remove foreign matter from the disk surface. This results in an increase in soft errors.

In an example of the prior art, the lifter thickness is increased from 75 μm to 1 μm for the purpose of improving the cleaning effect of the liner.
Attempts have been made to increase the thickness of the liner to 00 μm or 300 μm to improve the elastic contact effect of the liner with the magnetic disk, but the improvement in the cleaning effect with this method is temporary because the thermoelastic recovery rate of the lifter is not taken into account. Especially from 60℃
Under high temperature conditions of 90°C, the bending angle α of conventional polyethylene terephthalate lifters rapidly decreases to 0°.
, the cleaning effect rapidly decreases and the soft error reduction effect disappears.

[0010] Furthermore, if the thickness of the lifter is made so thick that the cleaning effect is not reduced, the rotational torque of the disk will increase significantly and the disk will not rotate normally when the drive is inserted.

[0011] The increase in soft errors due to the reduced cleaning effect becomes more pronounced as the recording density of the magnetic disk increases. Therefore, nowadays the linear recording density of magnetic disks is 17
For magnetic disks whose KBPI has further increased to 30 KBPI or more, the reduction in the cleaning effect described above causes a serious problem of increased soft errors.

As another method for preventing such deterioration of the cleaning effect, the use of metal flakes having a high initial elastic modulus, such as stainless steel flakes, has been considered.
This method also causes the rotational torque to increase over time, or the hard edges may scratch the surface of the magnetic disk or medium, so it is not yet a perfect solution.

[0013]

[Problems to be Solved by the Invention] Floppy disks housed in hard cases such as 3.5 inches are compliant with JIS and ANS standards.
It is specified to perform a specified function under certain environmental conditions specified in I. However, as magnetic disk cartridges have become widely and easily used in recent years, it has become common for magnetic disk cartridges to be exposed to high temperature environmental conditions of 60° C. to 90° C. A first object of the present invention is to provide a lifter and a magnetic disk cartridge that are improved so that even when exposed to such high-temperature environmental conditions, the cleaning effect is less reduced and the soft error rate is stably low. That is.

Another object of the present invention is to reduce soft errors in magnetic disk cartridges containing magnetic disks with high linear recording density by using an improved lifter and an improved non-magnetic support for magnetic disks. The aim is to reduce the

[0015]

[Specific Solution to the Problems] The present invention provides a lifter for magnetic disks and cartridges in which a liner made of non-woven fabric is brought into elastic contact with the surface of the magnetic disk, the lifter comprising:
(i) Thickness 50-200
μm(ii) Breaking elongation 10-100
%(iii) Young's modulus 150-1000
kg/mm2, and the lifter has (iv) a thermoelastic recovery rate ≧50
%, it has a high ability to clean dust etc. adhering to the magnetic disk surface, and even after being exposed to a wide range of environmental conditions, the cleaning effect does not decrease much, and soft errors are kept at a low level. lifter and magnetic disk cartridge.

The thermoelastic recovery rate referred to in the present invention means that when a load of 1.0 g is applied from the top of the lifter as shown in FIG.
After 72 hours at 90° C., the lifter was further returned to room temperature, and after 24 hours, the lifter's float Hmm was divided by the original lifter's float Ho and multiplied by 100 (%).

[0017] A lifter having a thermoelastic recovery rate ≧50% is impossible with the conventionally used polyethylene terephthalate film, and the glass transition temperature (Tg: °C)
A film made of a material having a temperature exceeding 100°C, more preferably 105°C or higher, and even more preferably 110°C or higher is used.

Films made of such materials include polyesters such as polyethylene-2,6-naphthalate and polyethylene 4,4'-diphenylate, U-polymer {poly P,P'-isopropylidene terephthalate isophthalate (manufactured by Unitika)}, and Elmec. F1100 {Kanebuchi Chemical

[0019]

Fully aromatic polyesters such as those whose main repeating unit is
The product name called K) is Sumilight FS110.
0 (Sumitomo Bakelite) {

[0020]

[Chemical 2] as the main repeat unit}, polysulfone (P
The product name called SO) is SUMILITE FS12.
00 (Sumitomo Bakelite) {

[0021]

[Chemical 3] is the main repeating unit}, is called polyether sulfone (PES) and its trade name is Sumilite FS.
1300 (Sumitomo Bakelite) {

[0022]

[Chemical formula 4] as the main repeating unit}, poly P, P'-isopropylidene diphenyl carbonate, and the trade name of polyimide are Upilex R (Ube Industries)
{

[0023]

[Chemical formula 5] as the main repeating unit}, Lark-TPI (
Mitsui Toatsu) {

[0024]

[C6] as the main repeating unit}, etc.

However, even if the above film or sheet is used, it is not always possible to obtain the desired thermoelastic recovery rate. In order to obtain a lifter having the desired thermoelastic recovery rate, the sheet or film used must be hot-stretched or heat-set, that is, it must be sufficiently stretched and oriented and have an elongation at break of 20 to 200%. need to use.

If the elongation at break is less than 20%, it may buckle during processing, and if it exceeds 200%, spherulites will develop during heat processing, which is undesirable. . The elongation at break is preferably 30 to 15
0% is selected.

In order to form a raw material sheet or film into a predetermined shape, the glass transition temperature (
Tg: °C) to flow start temperature (Tm: °C), more preferably {Tg+(30/100)(Tm-Tg)} to Tm-
5°C, more preferably {Tg+(50/100)(T
m-Tg)} to Tm-10 and heat-setting for 1 second to 5 minutes. The heat fixing time is preferably selected from a range of 2 seconds to 4 minutes, more preferably from 3 seconds to 3 minutes.

The rising angle α of the lifter formed in this manner is set to an angle between 7° and 45°. This angle is adjusted to a desired angle while measuring the rotational torque of the disk.

What is important during the above-mentioned bending process is to prevent the film from buckling. If buckled, it is natural that it will be difficult to obtain the thermoelastic recovery rate referred to in the present invention, but in extreme cases it may even break.

Furthermore, during the bending process, it is also important to avoid scratches along the fold line.

In this sense, it is a preferable processing method to bend the material not linearly but with a constant curvature.

The size of the lifter is the size of the free end excluding the adhesive part for fixing it to the hard case, which is approximately 20 m.
Although approximately m×20 is necessary to cover all tracks of the magnetic disk, it can be freely selected within the range of the size of the hard case depending on the purpose.

A magnetic disk cartridge using the lifter of the present invention is produced by fixing the lifter of the present invention to a hard case used for 3.5-inch, 3-inch, etc. magnetic disks, and using the lifter to bring the liner into elastic contact with the magnetic disk. It can be manufactured using

Examples of materials for the liner nonwoven fabric used in the magnetic disk cartridge of the present invention include rayon,
Examples include polyester. The thickness of the liner is preferably in the range of 0.13 to 0.30 mm (20 g/cm2 load). Depending on the thickness and initial elastic modulus of the lifter used, the thickness of the liner can be selected to reduce rotational torque and improve cleaning performance.

[0035] The magnetic disk cartridge, which has an improved cleaning effect due to such a structure, has a serious problem of soft errors, as described above. It exhibits a remarkable lift effect in magnetic disk cartridges containing magnetic disks with high linear recording density.

Furthermore, conventional magnetic disks have a magnetic recording layer provided on polyethylene terephthalate film (PET film) as a nonmagnetic support, but under the environmental conditions of 60° C. to 90° C., which is the object of the present invention. The PET film begins to wave, and especially around the metal hub in FIG. 1, distortion may occur due to the difference in thermal expansion coefficient between the metal hub and the PET film, and large waves may occur on the film surface.

The undulations generated on the surface of the magnetic disk hinder the accurate transmission and reception of signals between the magnetic disk and the drive, and cause a different kind of error problem from the increase in soft errors due to the deterioration of the cleaning effect described above.

[0038] To prevent such waviness, it is effective to use a crystalline film with a glass transition temperature of over 100°C in place of the conventionally used PET film. Examples of such films include polyethylene-2,6-naphthalate, polyethylene-4,4'-diphenylate, polyetheretherketone, and the like.

Among these, polyethylene-2,6-naphthalate film is preferably used from the viewpoint of additive stability.

In the magnetic disk cartridge of the present invention containing a magnetic disk in which a magnetic recording layer is provided on a polyethylene-2,6-naphthalate film, the magnetic disk cartridge of the present invention can be heated at temperatures of 60°C to 90°C.
Even when exposed to an environmental condition of 0° C., the cleaning effect hardly deteriorates, and the above-mentioned error problem can be suppressed to a low level.

[0041]

EXAMPLES The present invention will be explained in detail below with reference to Examples, but the present invention is not limited to these Examples unless the scope of the description of the present invention is exceeded.

[Method for Measuring Rotational Torque] The rotational torque was determined by measuring the current value of the motor from the drive with the head unloaded. The current value before cartridge installation and the current value after cartridge installation were calculated.

[Method of Measuring Error Rate] The error rate, which indicates the soft error occurrence rate, was measured by the following method. Write and read data to the initialized disk cartridge using the “DB6” signal pattern as one pass.
The number of CRC error sectors occurring in 00,000 passes was calculated. A random test was performed for tracks 1 to 79 and sides of the magnetic disk as 0 and 1.

[Method for measuring flow starting point] Measured using an elevated flow tester.

[0045] Nozzle diameter 0.5mm Piston diameter 1.0
cm2 Load: 5 kg Length: 1.0 mm The temperature is raised at a heating rate of 10°C/min. The temperature at which the polymer begins to flow out from the nozzle.

[0046]

[Example 1] Polyethylene naphthalate biaxially oriented film with a thickness of 100 μm (elongation at break 100% Young's modulus 700
A rectangular lifter with a width of 21 mm and a length of 28 mm was punched out from a sheet of paper (kg/mm2), the bent part was heated to 200°C, bent to α = 10°, and heat-fixed at the same temperature for another 10 seconds to form the fixed part shown in Figure 3. Length S, lift part length L and α
A lifter with an angle of 10° was created.

[0047]S=　8mm L=18mm The thermoelastic recovery rate of this lifter was 98%.

The end of this lifter was adhesively fixed to the lower shell of the hard case. A magnetic disk cartridge was obtained using a 3.5-inch magnetic disk (manufactured in Reference Example 1) using a commercially available nonwoven fabric made of rayon and polypropylene fibers with a thickness of 0.25 mm as a liner.

The rotational torque and soft error occurrence rate of this magnetic disk cartridge were measured immediately after manufacture and after heat treatment at 80° C. for 72 hours. The results are shown in Table 1.

As shown in Table 1, the rotational torque and number of error sectors before and after the heat treatment showed good results with close torques and no errors.

[0051]

[Comparative Example 1] The lifter was made of a 100 μm thick polyethylene terephthalate biaxially oriented film (breaking elongation 120%,
A lifter was prepared in the same manner as in Example 1 using a Young's modulus of 500 kg/mm2. However, the heating temperature was 150°C. The thermoelasticity and recovery rate of this lifter were 10%. Thereafter, a magnetic disk cartridge was produced in the same manner as in Example 1. The rotational torque and number of error sectors are shown in Table 1.
Both the torque and error rate before heat treatment were almost normal. However, after heat treatment, the torque significantly decreased and the error rate also significantly worsened. These results are also shown in Table 1.

[0052]

[Comparative Example 2] Width 21 mm from 100 μm thick polyethylene-2,6-naphthalate film wound around core
A rectangular lifter with a length of 28 mm was cut out, and a lifter having the same floating width H as in Example 1 as shown in FIG. 2 was produced.

The thermoelastic recovery rate of this lifter was 45%. The results of using the comparative lifter are also shown in Table 1.

[0054]

[Table 1]

[0055]

Examples 2 to 10 The effects of the improved lifter and magnetic disk cartridge will be illustrated by Examples 2 to 10. The results of Examples 2 to 6 are shown in Table 1. Also, Example 7~
The results of 10 tests are shown in Table 2.

[0056]

[Table 2]

The explanation of the production example is as follows.

[0058]

[Reference Examples 1 and 2] Cobalt-coated γ-ferrite
65 parts by weight Coercive force 740 Oe Specific surface area 20 m2 /g Polyurethane
5 parts by weight (Pandex T-5250 manufactured by Dainippon Ink Chemical Co., Ltd.) Polyurethane
5 parts by weight (Toyo Morton Co., Ltd. CA118) PVC/PVC (Doshin Chemical Co., Ltd. TA-5C) 6 parts by weight α-alumina (Sumitomo Chemical Akp-20) 7
Weight part carbon black
6 parts by weight oleyl oleate
6 parts by weight cyclohexanone
After mixing and dispersing 400 parts by weight or more of the composition using a sand glider, Coronate L
A magnetic paint was prepared by mixing 10 parts by weight (low molecular weight polyurethane from Nippon Polyurethane Co., Ltd.) in a high-speed disperser. The obtained magnetic paint was heated to 15℃2
Polyethylene terephthalate film with a thickness of 75 μm after aging for 4 hours (Reference Example 1) or polyethylene-2
, 6-naphthalate film (Reference Example 2) to a dry thickness of 1.0 μm, non-oriented treatment, drying, forming a magnetic layer, and then calendering. Furthermore, the same treatment was carried out on the back side. 60℃, 10
After heat treatment for 0 hours, a magnetic disk was punched out into a disk shape.

[0059]

[Reference Examples 3 and 4] Hexagonal barium ferrite
80 parts by weight Coercive force 750 Oe (Oersted) specific surface area 50 m2 /g Plate ratio 7 Polyurethane
4 parts by weight (Toyo Morton CA
118) PVC/Vinyl acetate (manufactured by Nippon Zeon MR110) 4 parts by weight PVC/vinyl acetate (manufactured by Doshin Chemical Co., Ltd. TA-5C) 4
Weight part α-alumina (Sumitomo Chemical Akp20)
4 parts by weight carbon black
3 parts by weight oleyl oleate
4 parts by weight cyclohexanone
Composition of 400 parts by weight or more using a sand glider,
After mixing and dispersing Coronate L
A magnetic paint was prepared by mixing 10 parts by weight (low molecular weight polyurethane from Nippon Polyurethane Co., Ltd.) in a high-speed disperser. The following operations were carried out in the same manner as in Reference Example 1, and the following discs were created.

[0060]

[0061]

[Reference Examples 5 and 6] Metal magnetic powder
100 parts by weight Specific surface area 42
m2 /g coercive force 1500 Oe PVC/PVC (MR110 manufactured by Nippon Zeon) 15 parts by weight polyurethane
15 parts by weight (Esten, Goodrich) α-alumina (Akp20, manufactured by Sumitomo Chemical) 4 parts by weight Carbon black
7 parts by weight butyl stearate
3 parts by weight oleyl oleate
3 parts by weight cyclohexanone
After mixing and dispersing 400 parts by weight or more using a sand glider, Coronate L
10 parts by weight (Nippon Polyurethane Co., Ltd.
(low molecular weight polyurethane) was mixed in a high-speed disperser to create a magnetic paint. The following discs were created in the same manner as in Reference Example 1.

[0062]

[Brief explanation of drawings]

FIG. 1 is an assembly diagram showing an example of a 3.5-inch magnetic disk cartridge.

FIG. 2 is a cross-sectional view of the lifter without creases.

FIG. 3 is a cross-sectional view of a creased lifter.

[Explanation of symbols]

1...Top shell 2...Center plate 3A, 3B...Liner 4...Metal hub 5...Adhesive 6...Magnetic disk 7...Lifter 8...Lower shell 9...Shutter 10...Shutter spring 11A, 11B...Magnetic head insertion slot 71A, 21B...Free end 72...Adhesive end 73...Fold line 74...Bending angle 75...Reference plane α…Bending angle H0...Lifter floating before heat treatment H...lifter floating after heat treatment

Claims (6)

[Claims] 1. A magnetic disk, a hard case capable of rotatably housing the magnetic disk, a cleaning liner provided inside the hard case, and a lifter provided between the hard case and the liner. In the magnetic disk cartridge, the lifter has (i) a thickness of
50-200 μm (ii)
Breaking elongation 10-100% (iii
) Young's modulus 150-1000 kg/mm2
and the lifter is made of a polymer film of (iv
) A magnetic disk cartridge that can exhibit excellent cleaning effects by having a thermoelastic recovery rate of ≧50%. 2. The magnetic disk is provided with a magnetic coating film containing at least cobalt-coated γ-ferrite magnetic powder and a binder on a non-magnetic support, and (i) the thickness of the magnetic coating film is 0.5. ~15
μm (ii) Coercive force of the magnetic coating film 600-80
0 Oe (iii) Linear recording density of the magnetic disk
2. The magnetic disk cartridge according to claim 1, wherein the magnetic disk is ≧15 KBPI. 3. The magnetic disk has a magnetic coating film containing at least barium ferrite magnetic powder and a binder provided on a non-magnetic support, and (i) the barium ferrite magnetic powder has an average particle size. Diameter: 0.01-0.1 μm Plate ratio: 2-10 (ii) Coercive force of the magnetic coating: 500-2000 Oe
Saturation magnetic charge ≧1000 Gauss, and vertical squareness ratio ≧0.5 (iii) Linear recording density of the magnetic disk ≧30
The magnetic disk cartridge according to claim 1, wherein the magnetic disk cartridge is KBPI. 4. The magnetic disk comprises a magnetic coating film containing at least a ferromagnetic (alloy) metal magnetic powder and a binder, (i) the ferromagnetic (alloy) metal magnetic powder has a specific surface area ≧35 m2 /g ( ii
) Coercive force of the magnetic coating film: 100 to 2000 Oe
Saturation magnetic charge ≧1000 Gauss, and (
iii) Linear recording density of the magnetic disk ≧30 KB
The magnetic disk cartridge according to claim 1, wherein the magnetic disk cartridge is a PI. 5. A metal thin magnetic film is provided on a non-magnetic support, (i) the ferromagnetic coercive force is 800 to 3000 Oe;
Residual magnetic flux density ≧3000 Gauss, and (ii
2. The magnetic disk cartridge according to claim 1, wherein the magnetic disk cartridge has a linear recording density of ≧30 KBPI. 6. The magnetic disk cartridge according to claim 1, wherein the nonmagnetic support is a polyethylene naphthalate film.