JP2001134933A - Floppy (registered trademark) disk and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a floppy disk which has high recording density, small deformation quantity of a substrate and excellent characterirtics. SOLUTION: In the floppy disk having at least a flat layer, a magnetic layer and a protective layer on both surfaces of a flexible nonmagnetic supporting body, a relation: Ts=(Tg-Tc).(1-exp(-dg/(dg+dc)))+Tc is satisfied between glass transition temperature or thermal deformation temperature of the supporting body (Tg: deg.C), thickness of the supporting body (dg: μm), thermal deformation/decomposition temperature of the flat layer (Tc: deg.C), thickness of the flat layer (dc: μm) and maximum substrate temperature set at the time of manufacturing the floppy disk (Ts: deg.C) and further substrate temperature at the time of manufacturing the floppy disk is below Ts ( deg.C).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a removable magnetic recording medium used for an auxiliary recording device of a computer, an image recording device, etc.
The present invention relates to a floppy disk having a high recording density of 6 terabits (1 gigabit per square inch) or more, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Tape-shaped magnetic recording media such as digital video tapes have been used as high-density recording media for large-capacity digital information such as auxiliary storage of computers. There is a demand for higher capacity and higher recording or reproduction speed. Due to these demands, a removable hard disk has recently been used as a large-capacity, high-density digital recording medium. However, the existing gigabyte-class removable media uses rigid disc-shaped substrates such as glass and aluminum, so when an impact is applied to the device, the media itself cannot absorb the impact, causing a head crash. However, both the magnetic recording medium and the head were sometimes seriously damaged. For this reason, those using a rigid substrate such as a removable hard disk have not yet solved the problem of impact resistance, and have problems in using a magnetic recording medium using the rigid substrate in a portable device. This is one of the problems in the spread of portable devices such as digital disk cameras using a magnetic recording medium using a rigid base.

[0003] By changing a rigid base to a flexible base, a magnetic recording medium can be reduced in weight of a recording portion, reduced in damage at the time of head crash, and realized a high-density removable magnetic recording medium excellent in impact resistance. It is possible. Therefore, the applicant has
We are developing ultra-high recording density recording media using flexible supports. The magnetic layer for high density recording is formed by a vacuum film forming method. When a vacuum film forming method is used for forming a magnetic layer of a floppy disk, a magnetic film having a high magnetic recording density can be manufactured. Among the vacuum film forming methods, the sputtering method in which the energy of the vapor-deposited particles is high is suitable for forming the magnetic layer of the magnetic recording medium used for such a purpose, but the collision energy of the vapor-deposited particles, contact with plasma generated during sputtering, Alternatively, the temperature of the support is increased by heating the support at a temperature of 50 to 300 ° C., which is performed to ensure the magnetostatic / electromagnetic conversion characteristics.

[0004] A high recording density magnetic recording medium requires a support having high flatness. When a hard disk is used as a support, flatness close to a mirror surface can be created by machining or the like. However, in the case of a floppy disk, it is difficult to improve the flatness by machining after production because an organic polymer substance is used as a support material. By providing a flat surface layer made of a substance, a surface property close to a mirror surface can be realized.

When a metal thin film is formed on a flexible support by vacuum film formation, the temperature of the support or a flat layer formed on the surface of the support increases. Since the support and the flat layer are made of an organic polymer material, they have a glass transition point or a heat distortion temperature. Therefore, when the temperature is excessively increased with respect to the glass transition point or the thermal deformation temperature, phenomena such as thermal deformation of the support / flat layer and generation of oligomers on the surface occur.

[0006] These phenomena cause static deformation of a floppy disk manufactured by vacuum film formation, and generate unsteady vibration when the disk rotates. The unsteady vibration generated by the rotation of the disk deteriorates the reading and writing characteristics of the signal between the head and the magnetic recording medium, and the substantial problem is that the actual characteristics of the floppy disk are lowered.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a floppy disk having improved characteristics, such as the amount of deformation and the number of concave portions, of a floppy disk having a high recording density and a large capacity. It is an object to provide

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a floppy disk having at least a flat layer, a magnetic layer and a protective layer on both sides of a flexible non-magnetic support. Deformation temperature (Tg: ° C),
Support thickness (dg: μm), thermal deformation / decomposition temperature of flat layer (Tc: ° C.), flat layer thickness (dc: μm), and maximum substrate temperature (Ts: ° C.) set at the time of manufacturing a floppy disk
Ts = (Tg−Tc) · (1-exp (−dg / (dg)
+ Dc))) + Tc, and the problem can be solved by a method of manufacturing a floppy disk in which the substrate temperature at the time of manufacturing the floppy disk is Ts (° C.) or lower. The present invention is the above-mentioned method for producing a floppy disk, wherein the thickness (dg) of the support is in the range of 20 to 200 μm. The present invention is the above-mentioned method for producing a floppy disk, wherein the thickness (dg) of the support is in the range of 30 to 80 μm.

Also, in a floppy disk having at least a flat layer, a magnetic layer, and a protective layer on both sides of a flexible non-magnetic support, the glass transition temperature or thermal deformation temperature (Tg: ° C.) of the support, the thickness of the support (Dg: μm), thermal deformation / decomposition temperature of the flat layer (Tc: ° C.), flat layer thickness (dc:
μm) and the maximum substrate temperature (Ts: ° C.) set at the time of manufacturing the floppy disk, Ts = (Tg−Tc) · (1-exp (−dg / (dg)
+ Dc))) + Tc, and is a method for manufacturing a floppy disk in the range of 30 ≦ dg ≦ 80 μm. Further, the present invention is a floppy disk manufactured by the above-mentioned method for manufacturing a floppy disk.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a method for manufacturing a floppy disk having at least a flat layer, a magnetic layer, and a protective layer on a flexible support by maintaining the substrate temperature at a specific temperature or lower. It has been found that curling during the production of a metal thin film can be prevented, and that the surface properties of a floppy disk can be prevented from lowering.

That is, in a floppy disk having at least a flat layer, a magnetic layer, and a protective layer on both sides of a flexible support substrate, the support has a glass transition temperature or heat deformation temperature (Tg: ° C.), and a support thickness. (Dg: μm), thermal deformation / decomposition temperature of the flat layer (Tc: ° C.), flat layer thickness (d
c: μm) and the maximum substrate temperature (Ts: ° C.) set at the time of manufacturing the floppy disk, Ts = (Tg−Tc) · (1−exp (−dg / (dg))
+ Dc))) + Tc is maintained, the curl during the production of the metal thin film by the vacuum film formation method can be prevented, and the surface property can be prevented from deteriorating.

When a metal thin film is formed on a flexible support by a vacuum film forming method, the temperature of the support or a flat layer formed on the surface of the support increases. Since the support and the flat layer are made of a polymer material, they have a glass transition point or a heat deformation temperature. Therefore, when the substrate temperature is excessively higher than the glass transition point or the heat deformation temperature during the manufacture of a floppy disk, the flexible support undergoes thermal deformation and is included in the flexible support or the composition for forming a flat layer. The generated oligomer is generated on the flat layer or the surface of the support, and the surface property is reduced.

Particularly when a material different from the polymer composition for forming the flat layer is used for the material constituting the flexible support, the flat layer is formed because the flexible support and the flat layer are laminated. A flexible support is formed in which the thermal characteristics of the layer and the flexible support are averaged, and the glass transition point or thermal deformation / decomposition temperature of both the material forming the flexible support and the flat layer is set as a parameter. It is considered that an effective glass transition temperature or thermal deformation / decomposition temperature exists.

It is considered that the thickness of the support and the flat layer, as well as the glass transition temperature of both the flexible support and the flat layer, have a great influence on the effective glass transition temperature or thermal deformation / decomposition temperature. Considering the case where the thermal deformation and decomposition temperature of the flat layer is higher than that of the flexible support, the polymer substance forming the flexible support and the flat layer has low specific heat and low thermal conductivity. Therefore, when the thermal deformation / decomposition temperature of the flat layer is high, it has an effect of preventing heat conduction to the flexible support. When the thickness of the flat layer is small, the heat blocking effect is reduced, and the amount of heat conduction to the flexible support is increased.
Conversely, if the flat layer is too thick, the heat blocking effect is improved, but it is not possible to follow the deformation of the flexible support when the substrate temperature rises, resulting in cracks.

Further, since the heat conduction is described by a first-order differential equation, the flexible support and the flat layer are analyzed by using the glass transition point or the heat deformation temperature and the layer thickness as parameters to obtain the flexible support. In a floppy disk having at least a flat layer, a magnetic layer, and a protective layer on both surfaces of a substrate, a glass transition temperature or a heat distortion temperature (T
g: ° C), the thickness of the support (dg: µm), the thermal deformation / decomposition temperature of the flat layer (Tc: ° C), the thickness of the flat layer (dc: µm), and the maximum substrate temperature set during the manufacture of the floppy disk ( Ts = (Tg−Tc) · (1-exp (−dg / (dg))
+ Dc))) + Tc, and the substrate temperature during manufacture of the floppy disk is T
It has been found that by setting the temperature to s (° C.) or less, it is possible to prevent thermal deformation during production of a floppy disk and a decrease in surface properties due to generation of oligomers.

Here, the glass transition point, the thermal decomposition temperature, the thermal deformation temperature, and the thickness are determined as follows. Glass transition point: heating the support or the flat layer material to a molten state. At this time, an endotherm at the time of phase transformation from a solid to a liquid is observed by a differential scanning calorimeter (DSC), and the temperature at the maximum absorbed heat is defined as a glass transition point. -Thermal decomposition temperature: The support or the flat layer material is heated on a thermobalance, and the temperature at which the mass of the polymer starts to decrease is defined as the thermal decomposition temperature. Heat deformation temperature: A sheet obtained by processing the indicator and flat layer material to a thickness of 50 μm is cut into a 1 cm × 1 cm strip.
After heating the sheet, it is cooled to room temperature. The sample of the cooled sheet is visually observed, and the heating temperature at which one or more undulations occur on the surface is defined as the heat deformation temperature. -Thickness: Ten sheets of the support are stacked, and the thickness is measured with a micrometer. The average support thickness calculated from the measured values is defined as the support thickness. Similarly, the average thickness of the flat layer is calculated by stacking 10 flat layer-formed supports. The thickness of the support was subtracted from this value to calculate the thickness of the flat layer.

As the flexible support used for the floppy disk of the present invention, polyethylene terephthalate,
Polyethylene naphthalate, polyimide, polyamide,
Materials such as polyamide imide and polybenzoxazole can be given.

The flexible support has a Young's modulus of 1.96.
Up to 15.69 GPa (200 to 1600 kgf / m
m ² ), particularly preferably from 2.94 to 7.85 GP.
a (300 to 800 kgf / mm ² ). The thickness of the support is 20 μm to 200 μm, more preferably 30 μm.
The range is from μm to 80 μm. When the thickness of the support is 20 μm or less, the static deformation (curl) of the flexible support increases, the surface runout increases when the disk rotates, and the stable contact between the head and the floppy disk is maintained. Can not. If the thickness exceeds 200 μm, the impact force when the head comes into contact with the floppy disk is strong, and the head or the floppy disk is damaged.

The flat layer is provided on the flexible support to improve the flatness of the flexible support. As the flat layer material, a substance generally used as a heat-resistant polymer material can be used. Particularly preferred are materials such as silicone resin, polyamide resin, polyamideimide resin, and polyimide resin. These materials are not only excellent in heat resistance, but also can achieve good surface properties and magnetostatic properties. The thickness of the coating layer after the curing of the flat layer is 0.1 μm to 5.0 μm. Preferably 0.5 μm
To 3.0 μm, particularly preferably 0.8 to 2.0 μm
m.

When the thickness of the coating layer is 0.1 μm or less,
The protrusion on the flexible support cannot be completely filled, and a sufficient output cannot be obtained because of a spacing loss. On the other hand, when the thickness is 5.0 μm or more, the flat layer cannot follow the thermal deformation of the flexible support, and cracks occur. Further, minute projections and depressions may be provided on the flat layer by providing minute projections on the surface of the flexible support. These projections are formed, for example, on the surface of a flexible support by SiO ₂ , Al ₂
It can be formed by providing inorganic fine particles such as O ₃ and TiO ₂ or organic fine particles. The particle size of the fine particles used is 5 nm to 50 nm, particularly preferably 10 n.
m to 40 nm. The projection formed on the surface of the flat layer by providing such fine particles on a flexible support preferably has a height of 2 nm to 40 nm. If the protrusion height on the flat layer surface is 2 nm or less, the frictional force between the magnetic head and the floppy disk increases, and the head or the floppy disk is damaged. If it is 40 nm or more, the spacing loss becomes remarkable, and sufficient recording / reproducing characteristics cannot be obtained.

As the underlayer, for example, the following Cr, T
i, Ni, W, Mo, V, Ta, B, Si, Nb, Z
Preferred are metals of r, Al, and Mn, alloys of at least two elements, or oxides, nitrides, and phosphides thereof. Particularly preferred is an alloy containing Cr as a main component, with a Cr concentration of 77 to 100 at%, particularly preferred is 80 to 95 at%, and the balance is other elemental metals. The thickness of the underlayer is 5 nm to 500 nm, and particularly preferably 10 nm to 100 nm. When the thickness of the underlayer is increased to 100 nm or more, the grain size of the magnetic layer increases, and the noise of the floppy disk increases.

As the magnetic material, a CoCr alloy, particularly an alloy containing Pt, Ta, Ni, Si, B, Ni and Pd, or an oxide or nitride is desirable. Among them, CoCrPt and CoCrPtTa are particularly preferred. Also C
A granular medium composed of an alloy containing o as a main component and a nonmagnetic material is also possible. The Cr concentration in the magnetic layer is 10
-30 at%, and particularly desirable is 15-25 at%.
%. The thickness of the magnetic layer is from 10 to 300 nm, particularly preferably from 15 to 60 nm.

The underlayer and the magnetic layer are preferably provided by a vacuum film forming method. In particular, a sputtering method is preferable because a film can be formed without changing the composition of elements constituting the raw material. It is preferable that the underlayer and the magnetic layer are successively formed while maintaining a vacuum state. The magnetic layer and the underlayer are preferably formed by a vacuum film forming method such as a direct current sputtering method or a high frequency sputtering method. Also, an underlayer,
In the case of heating the substrate when preparing the magnetic layer, a heating method using an infrared lamp, a heating method using heat generated by energizing a resistor, or the like can be used as a heating method.

The floppy disk of the present invention preferably has a protective film on the surface. The carbon protective film is preferably a carbon film made of amorphous carbon, graphite, diamond-like structure carbon, or a mixture thereof formed by a plasma CVD method, a sputtering method, or the like, and particularly preferably an amorphous hard film called diamond-like carbon. It is a carbon film. This hard carbon film has a Vickers hardness of 9.
It is a hard carbon film of 8 GPa (1000 kgf / mm ² ) or more, preferably 19.6 GPa (2000 kgf / mm ² ) or more. The thickness of the protective layer is preferably from 2.5 to 30 nm, particularly preferably from 5 to 25 nm.

In the magnetic recording medium of the present invention, in order to improve running durability and corrosion resistance, it is preferable to add a lubricant or a rust inhibitor to the magnetic film or the protective film. For example, hydrocarbon-based lubricants, fluorine-based lubricants, extreme pressure additives, and the like, which are used as lubricants in the above, can be used. Examples of the hydrocarbon-based lubricant include carboxylic acids such as stearic acid and oleic acid, esters such as butyl stearate, sulfonic acids such as octadecylsulfonic acid, phosphoric esters such as monooctadecyl phosphate, stearyl alcohol, oleyl alcohol and the like. Alcohols, carboxylic acid amides such as stearic acid amide, and amines such as stearylamine. Examples of the fluorine-based lubricant include lubricants in which part or all of the alkyl group of the hydrocarbon-based lubricant is substituted with a fluoroalkyl group or a perfluoropolyether group. Examples of the perfluoropolyether group include a perfluoromethylene oxide polymer, a perfluoroethylene oxide polymer, a perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) _n , and a perfluoroisopropylene oxide polymer (CF ( CF ₃₎ a CF ₂ O) _n or copolymers thereof.

Examples of extreme pressure additives include phosphoric esters such as trilauryl phosphate, phosphites such as trilauryl phosphite, thiophosphites and thiophosphoric esters such as trilauryl trithiophosphite, and the like. And sulfur-based extreme pressure agents such as dibenzyl sulfide.

The above lubricants may be used alone or in combination.
used. Apply these lubricants on the magnetic film or protective film.
As a method of imparting water to a lubricant, a lubricant is dissolved in an organic solvent
Ear bar method, gravure method, spin coating method, dip
Apply by a coating method or adhere by vacuum evaporation.
Just do it. The amount of lubricant to be applied is 1 to 30 mg / m ^Two
Is preferably 2 to 20 mg / m^Two Is particularly preferred.

The rust preventives usable in the present invention include nitrogen-containing heterocyclic compounds such as benzotriazole, benzimidazole, purine and pyrimidine, derivatives having an alkyl side chain or the like introduced into their nucleus, benzothiazole, 2-benzothiazole, and the like.
Examples thereof include nitrogen- and sulfur-containing heterocyclic compounds such as mercapton benzothiazole, tetrazaindene ring compounds, and thiouracil compounds, and derivatives thereof.

[0029]

The present invention will be described below with reference to examples and comparative examples. Example 1 A 1.7 μm-thick silicone resin flat layer was applied to both sides of a 63 μm-thick polyethylene naphthalate support. Using a sputtering apparatus (S-50S, manufactured by Shibaura Seisakusho), an argon partial pressure of 2.0 Pa (1) was formed on the flat layer on the flexible support.
Under a condition of 5.0 mTorr), an input power of 12.0 W / cm ² , and a substrate temperature of 150 ° C., a nonmagnetic underlayer made of a CrTi 20 at% alloy was coated with a thickness of 60 nm. On the obtained metal underlayer, a Co alloy thin film having a thickness of 30 nm as a metal magnetic film and containing 20 atomic percent of Cr and 12 atomic percent of Pt was coated with an argon partial pressure of 0.107 Pa.
(0.8 mTorr), input power 12.0 W / cm ² ,
A magnetic recording medium was manufactured at a substrate temperature of 150 ° C.
Next, the obtained magnetic recording medium was punched into a 3.5-inch type to produce a floppy disk. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

In the apparatus, the position of the substrate surface and the temperature control thermocouple are separated from each other. Therefore, the thickness 50μm
A thermo label is stuck on the holder on which the polyimide film is placed, and calibration is performed so that the thermo label temperature and the thermocouple indication value become equal from the relationship between the temperature by the thermo label and the measurement value of the thermocouple. After the calibration, the heating temperature on the flat layer surface was determined using the thermocouple indicated value.

Example 2 A floppy disk was manufactured under the same conditions as in Example 1 except that the thickness of the flat layer was changed to 6.0 μm. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 3 A floppy disk was manufactured under the same conditions as in Example 1 except that the substrate temperature was changed to 80 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 4 A floppy disk was manufactured under the same conditions as in Example 2 except that the substrate temperature was changed to 80 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 5 A floppy disk was manufactured under the same conditions as in Example 1 except that the substrate temperature was changed to 30 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 6 A floppy disk was manufactured under the same conditions as in Example 1 except that the substrate temperature was changed to 30 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 7 A flexible support was made of 63 μm polyethylene terephthalate.
A floppy disk was manufactured under the same conditions as in Example 1 except that the substrate temperature was changed to 110 ° C. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Example 8 Example 1 except that the thickness of the flat layer was changed to 6.0 μm.
A floppy disk was produced under the same conditions as described above. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 9 A floppy disk was manufactured under the same conditions as in Example 7 except that the substrate temperature was changed to 60 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 10 A floppy disk was manufactured under the same conditions as in Example 8 except that the substrate temperature was changed to 60 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 11 A floppy disk was manufactured under the same conditions as in Example 7 except that the substrate temperature was changed to 30 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 12 A floppy disk was manufactured under the same conditions as in Example 8 except that the substrate temperature was changed to 30 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 13 A floppy disk was manufactured under the same conditions as in Example 1 except that the material of the flat layer was changed to polyimide resin. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 14 A floppy disk was manufactured under the same conditions as in Example 13 except that the thickness of the flat layer was changed to 6.0 μm. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Comparative Example 1 A floppy disk was manufactured under the same conditions as in Example 1 except that the substrate temperature was changed to 180 ° C. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 2 A floppy disk was manufactured under the same conditions as in Example 2 except that the substrate temperature was changed to 180 ° C. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 3 A floppy disk was produced under the same conditions as in Comparative Example 1 except that the thickness of the flat layer was changed to 10 μm. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 4 A floppy disk was manufactured under the same conditions as in Comparative Example 1 except that the thickness of the flat layer was changed to 20 μm. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 5 A floppy disk was manufactured under the same conditions as in Example 7 except that the substrate temperature was changed to 160 ° C. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 6 A floppy disk was manufactured under the same conditions as in Example 8 except that the substrate temperature was changed to 160 ° C. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 7 A floppy disk was manufactured under the same conditions as in Comparative Example 5, except that the thickness of the flat layer was changed to 10 μm. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 8 A floppy disk was manufactured under the same conditions as in Comparative Example 5 except that the thickness of the flat layer was changed to 20 μm. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 9 A floppy disk was manufactured under the same conditions as in Example 13 except that the substrate temperature was changed to 220 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Comparative Example 10 A floppy disk was manufactured under the same conditions as in Example 14 except that the substrate temperature was changed to 220 ° C. The obtained floppy disks were evaluated by the following evaluation methods, and the results are shown in Table 1.

Comparative Example 11 A floppy disk was manufactured under the same conditions as in Comparative Example 9 except that the thickness of the flat layer was changed to 10 μm. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

Comparative Example 12 A floppy disk was manufactured under the same conditions as in Comparative Example 9 except that the thickness of the flat layer was changed to 20 μm. The obtained floppy disk was evaluated by the following evaluation method,
Table 1 shows the results.

(Evaluation Method) (1) Deformation: Curl Amount and Number of Depressions The center of the obtained floppy disk is inserted into a holding rod having a diameter of 25 mm which is the same as the inner diameter of a horizontally fixed floppy disk. With the holding plate, the floppy disk is fixed vertically and the influence of gravity is removed. Using a laser displacement meter from a direction parallel to the axis of the holding rod, the disk is used for one round every 1 cm from the center of the floppy disk. Measure the displacement. The difference between the most convex part and the most concave part of the floppy disk was defined as the curl amount. Regarding the non-uniform deformation of the disk, the number of concave portions having a height of 0.3 mm from the minimum height of the disk at the outer periphery of the disk was measured and evaluated. Those having up to two concave portions have good characteristics.

(2) Occurrence of Oligomer In a magnification of 80 times with a differential interference microscope, 10 visual fields were observed at random. If at least one visual field generated oligomer, it was regarded as defective. (3) Crack generation After sputtering, the sample was cooled and the sample surface was observed with a differential interference microscope. Twenty-three observations were made at random at a magnification of 200 times. The case where no crack was observed among the 30 measurement points was evaluated as excellent.

[0058]

[Table 1] Tg dg Tc dc Ts Substrate temperature Curl Number of recesses Oricommer crack (° C) (μm) (° C) (μm) (° C) (° C) (mm) (pieces) Example 1 113 63 250 1.7 164.74 150 0.2 1 Good Excellent Example 2 113 63 250 6 167.98 150 0.1 1 Good Good Example 3 113 63 250 1.7 164.74 80 0.1 0 Good Excellent Example 4 113 63 250 6 167.98 80 0.1 0 Good Good Example 5 113 63 250 1.7 164.74 30 0.1 0 Good Excellent Proposal 6 113 63 250 6 167.98 30 0.1 0 Good Excellent Example 7 69 63 250 1.7 137.36 110 0.3 1 Good Excellent Example 8 69 63 250 6 141.64 110 0.22 Good Good Example 9 69 63 250 1.7 137.36 60 0.3 2 Good Excellent Example 10 69 63 250 6 141.64 60 0.2 1 Good Good Example 11 69 63 250 1.7 137.36 30 0.1 1 Good Excellent Example 12 69 63 250 6 141.64 30 0.1 1 Good Excellent Example 13 113 63 340 1.7 198.73 190 0.2 1 Good Excellent Example 14 113 63 340 6 204.10 190 0.3 1 Good Good Comparative Example 1 113 63 250 1.7 164.74 180 0.8 3 Poor Excellent Comparative Example 2 113 63 250 6 167.98 1 80 1.6 4 Poor Good Comparative Example 3 113 63 250 10 170.80 180 1.9 3 Good Poor Comparative Example 4 113 63 250 20 177.13 180 3.1 4 Good Poor Comparative Example 5 69 63 250 1.7 137.36 160 1.1 3 Poor Excellent Comparative Example 6 69 63 250 6 141.64 160 1.9 4 Poor Good Comparative Example 7 69 63 250 10 145.36 160 2.2 3 Poor Good Comparative Example 8 69 63 250 20 153.73 160 3.1 4 Poor Poor Comparative Example 9 113 63 340 1.7 198.73 220 1.1 3 Good Excellent Comparative Example 10 113 63 340 6 204.10 220 1.9 4 Good Good Comparative Example 11 113 63 340 10 208.77 220 2.3 3 Good Good Comparative Example 12 113 63 340 20 219.26 220 3.1 4 Good Bad

[0059]

According to the present invention, the temperature conditions and the like at the time of vacuum
Since it was set in a predetermined range by various parameters,
A magnetic recording medium having a small amount of mechanical deformation and excellent characteristics with few cracks or the like was obtained.

Claims (4)

[Claims] 1. A floppy disk having at least a flat layer, a magnetic layer, and a protective layer on both sides of a flexible non-magnetic support, wherein the support has a glass transition temperature or thermal deformation temperature (Tg: ° C.), and a support thickness. (Dg: μm), thermal deformation / decomposition temperature of the flat layer (Tc: ° C.), flat layer thickness (dc: μm)
m) and the maximum substrate temperature (Ts: ° C.) set at the time of manufacturing the floppy disk, Ts = (Tg−Tc) · (1-exp (−dg / (dg)
+ Dc))) + Tc, wherein the substrate temperature during the production of the floppy disk is Ts (° C.) or lower. 2. The support has a thickness (dg) of 20 to 200 μm.
2. The method for manufacturing a floppy disk according to claim 1, wherein 3. A flat layer thickness (dc) of 0.1 to 5.0 μm.
3. The method of manufacturing a floppy disk according to claim 1, wherein the value is in the range of m. 4. A floppy disk manufactured by the method for manufacturing a floppy disk according to claim 1.