JP2001216629A - Substrate for floppy disk and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a floppy disk, having high dimensional stability and heat resistance, and the floppy disk. SOLUTION: The substrate 1A for the floppy disk is manufactured by thermally adhering a heat resistant resin films 4 onto both surfaces of a thermo plastic resin film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support for a floppy disk having a high recording density and a method for producing the same, and more particularly to a support having high dimensional stability and heat resistance, low warpage and a smooth surface. And a method of manufacturing the same.

[0002]

2. Description of the Related Art In a magnetic recording medium, as a method for forming a magnetic layer, a coating type magnetic recording medium in which a ferromagnetic powder is dispersed in a binder, a ferromagnetic metal thin film on a support by a sputtering method or the like. A magnetic recording medium composed of a ferromagnetic metal thin film manufactured by a vacuum film forming method such as an evaporation method is used. The ferromagnetic metal thin film formed by the vacuum film forming method can easily obtain high magnetic energy, and it is easy to make the surface of the magnetic layer smooth by smoothing the surface of the nonmagnetic substrate. It is suitable for a high-density recording material because it has a small spacing loss and high electromagnetic conversion characteristics. In particular, a magnetic layer obtained by a sputtering method can increase the magnetic energy as compared with a magnetic layer obtained by a vapor deposition method, and thus is used for a medium requiring a high recording density such as a hard disk.

On the other hand, floppy disk type magnetic recording media are widely used because of their superior impact resistance and low cost as compared with hard disks. Further, the present applicant has proposed a 3.5-type floppy disk 1 by using a coating type magnetic recording medium in which a thin magnetic layer is formed by applying a magnetic paint on a lower magnetic layer formed on a base or a lower non-magnetic layer. A large-capacity medium exceeding 100 MB per sheet is provided. However, its recording density is still 1/10 or less of that of a hard disk. This is largely due to the fact that although many attempts have been made to produce a magnetic layer by a sputtering method like a hard disk, it has not yet been put to practical use.

There are various reasons for this. One of the reasons is that it is difficult to develop a support suitable for such a floppy disk. The support of a floppy disk on which a magnetic layer is formed by a sputtering method is required to have at least the following four characteristics. (1) Smooth surface property When a magnetic recording medium is manufactured by a sputtering method, the surface property of the support is directly reflected on the surface property of the medium. A support having a smooth surface is required. Specifically, a support having a maximum surface roughness _Rmax of 60 nm or less is required. (2) High heat resistance The magnetic layer for high-density recording needs electromagnetic conversion characteristics such as high output and low noise. For this reason, when the magnetic layer is formed by sputtering, the film is formed while heating the support. Must. For this reason, the support is required to have extremely high heat resistance, and must be stable without causing deformation or chemical change even during heating. Specifically, the support must have heat resistance of 200 ° C. or higher.

(3) Less warpage In a high-density floppy disk, to increase the transfer speed,
While rotating at high speed like a hard disk, it slides at a very low flying height in contact with or close to the magnetic head. If the floppy disk runs out of surface, the floppy disk comes into strong contact with the head and the sliding becomes unstable, leading to deterioration in running durability and reliability. For this reason, it is necessary to keep the surface deviation of the floppy disk to 50 μm or less. Such run-out is strongly influenced by the static sled of the floppy disk. This warpage may be caused by a difference in stress between the front and back sides of the magnetic recording medium during the manufacturing process of the magnetic recording medium when the support originally has the warp. Although the warpage generated in the manufacturing process can be adjusted by the process conditions, the warpage inherent to the support is very difficult to adjust by the process conditions because the thickness of the support is much larger than the thickness of the magnetic layer. It is. In addition, when a polyimide or polyamide film having high heat resistance is used as the support, the material has high heat resistance, so that the shape cannot be corrected by heating. For this reason, it is necessary for the support to have almost no static warpage.
Specifically, it is necessary to press down to 1 mm or less in a state of being punched into a 3.5-type disk shape. (4) Dimensional stability Recent floppy disks are considered to be used inside notebook PCs due to the spread of notebook PCs. However, the temperature inside the notebook PC is high, and notebook PCs are carried around. They are often used over a wide temperature range. In such a situation, the floppy disk needs to have excellent dimensional stability with respect to temperature and be capable of stable tracking. For this purpose, the support must have excellent thermal dimensional stability.

It is very difficult to develop a support that satisfies the above four required properties, and it is not commercially available. For example, polyethylene terephthalate and polyethylene naphthalate, which are widely used as supports for magnetic tapes and floppy disks, have a glass transition temperature much lower than the heating temperature when forming a magnetic layer by a sputtering method. In many cases, deformation occurs when the layer is formed, and cracks often occur in the magnetic layer. When heated to such a temperature, the surface properties of the oligomer are significantly deteriorated due to the precipitation of the surface of the oligomer.

Although heat-resistant resin films such as aromatic polyimides and aromatic polyamides have sufficient heat resistance, it is difficult to realize smooth surface properties and low warpage due to problems in their production. Further, it is difficult to produce a polyamide film having a thickness of 50 μm or more. Further, polyimide and aramid films are expensive, and thus account for a large proportion of the manufacturing cost of the floppy disk to be manufactured. Further, no matter what kind of material is used, if the surface is smoothed to a certain degree or more, handling such as transporting and winding the support becomes very difficult. In order to solve this problem, it is necessary to intentionally create irregularities near the end surface of the support to prevent sticking to the conveying member or the back surface of the support, but even if this method is used, the width of the support may be reduced. If it is widened to some extent, the effect is reduced and the handling characteristics are deteriorated.

For this reason, in order to produce a support satisfying the above-mentioned required properties, it is necessary to process an existing film to improve the properties of the support. As such a method, a method in which a heat-resistant film such as a polyimide or a polyamide is laminated and attached to each other to produce a support made of a laminate can be considered. By using this method, even when the film is waiting for warpage, it is possible to greatly reduce the warpage by bonding the films in directions that cancel each other. Also, it is not always necessary for both surfaces to be smooth. One surface is made as smooth as possible, the other surface is roughened to facilitate handling, and the rough surfaces are bonded together to produce a support having both surfaces smooth. It is possible.

However, the conventional method of laminating using a general-purpose epoxy-based adhesive is insufficient in heat resistance of the adhesive. There was a problem that the temperature significantly decreased or volatile gas was generated by thermal decomposition. In the method of laminating using a thermosetting polyimide having sufficient heat resistance as an adhesive, the thermosetting polyimide is dissolved only in a specific high boiling point solvent, and it is difficult to completely remove this solvent. For this reason, there is a problem that air bubbles are generated on the bonding surface in the thermosetting process for bonding. Furthermore, when another thermosetting or thermoplastic resin having high heat resistance is applied by dissolving in a solvent and used as an adhesive, the viscosity of the adhesive is high, and it is not possible to remove foreign substances by precise filtration of the adhesive. Because it is possible,
There is a problem that foreign matter is easily mixed into the bonding surface.

For example, there has been proposed a method of bonding a heat-resistant polymer film having a magnetic layer formed thereon to a substrate film via an adhesive as disclosed in Japanese Patent Application Laid-Open No. Hei 8-249641. This requires a coating process for forming a film, and foreign matter is apt to be mixed into the adhesive surface, or the warpage of the base film affects the floppy disk, so that a floppy disk with little warping cannot be produced.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a floppy disk having smooth surface properties, high heat resistance, low warpage, and high dimensional stability.

[0012]

The object of the present invention can be solved by a floppy disk support in which a heat-resistant resin film is heated and bonded to both sides of a thermoplastic resin film. The above-mentioned support for a floppy disk, wherein the heat-resistant resin films present on both surfaces of the support are selected from aromatic polyamide films and aromatic polyimide films. The above-mentioned floppy disk support, wherein the thermoplastic resin film is selected from the group consisting of polyetherimide, polyethersulfone, polysulfone, polyetheretherketone, fluororesin, and polyimide. The above-mentioned support for a floppy disk, wherein the undercoat layer is provided on both surfaces of the surface of the heat-resistant resin film and smoothed. The above-mentioned floppy disk support, wherein the undercoat layer is made of either thermosetting polyimide or thermosetting silicone resin.

In the method for manufacturing a floppy disk, a magnetic layer may be provided on the floppy disk support.
This is a method for manufacturing a floppy disk on which a protective layer is formed. Further, in the method for producing a floppy disk support, a heat-resistant resin film is laminated on both surfaces of a thermoplastic resin film, flat-pressed, and then heated and adhered and integrated to form a floppy disk support. In the method for producing a floppy disk support, the heat-resistant resin film is laminated on both surfaces of a thermoplastic resin film, and heated and pressed with a heating roller to be bonded and integrated to form the floppy disk support.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, the present invention provides a heat-resistant film having a magnetic layer formed on the surface and having excellent surface smoothness.
Large heat resistance of laminated and heat-bonded on both sides of the thermoplastic resin film, large, no warpage, and a floppy disk support with high surface smoothness is obtained.Floppy disks manufactured using this support are: They have found that they have excellent electromagnetic conversion characteristics.

FIG. 1 is a sectional view for explaining a floppy disk support of the present invention. The support 1A for a floppy disk of the present invention has a heat-resistant resin film 4 laminated on both surfaces of a thermoplastic resin film 2.
Since the heat-resistant resin films 4 on both sides were bonded by heating using the thermoplastic resin film 2, no adhesive was used for laminating the both. As a result, the heat resistance of the surface was large, and the occurrence of warpage was small. Therefore, after forming an undercoat layer or the like on the surface of the heat-resistant resin film, the magnetic layer was formed by a vacuum deposition method such as a vacuum deposition method or a sputtering method. Thereafter, a protective layer, a lubricating layer, and the like are formed to obtain a floppy disk having excellent heat resistance and excellent electromagnetic conversion characteristics.

FIG. 2 is a view for explaining a floppy disk using the floppy disk support of the present invention.
It is sectional drawing. In the floppy disk 1B of the present invention, a heat-resistant resin film 4 having a magnetic layer 3 formed on both surfaces of a thermoplastic resin film 2 is laminated. If the smoothness of the surface of the heat-resistant resin film 4 is insufficient, a magnetic layer having a smooth surface cannot be obtained. Therefore, the undercoat layer 5 may be formed on the heat-resistant resin film 4. On the undercoat layer 5, an underlayer 6 is provided for the purpose of improving the magnetostatic properties of the magnetic layer.
Is formed, and the magnetic layer 7 is formed thereon. Also,
In order to control the crystal orientation of the underlayer 6, the seed layer 8 may be formed prior to the formation of the underlayer 6, and the seed layer 8 may be adhered to improve the adhesion between the underlayer 6 or the seed layer 8 and the undercoat layer 5. The layer 9 may be formed. Further, a protective layer 10 and a lubricating layer 11 are formed on the magnetic layer 6.

The heat-resistant resin film used in the present invention includes:
Aromatic polyimide film, aromatic polyamide film, polyetheretherketone, polyethersulfone, polyetherimide, polysulfone, polyphenylene sulfide, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), alkyl vinyl ether copolymer (PFA) And a heat-resistant resin film such as a fluororesin selected from tetrafluoroethylene-ethylene copolymer (ETFE) and chlorotrifluoroethylene resin (CTFE). Among these, a polyimide film and a polyamide film are preferable from the viewpoint of heat resistance. This is because the surface of the substrate reaches a high temperature due to the heating of the heat-resistant resin film used as the substrate when forming the magnetic layer by sputtering and the heat of the plasma during the formation, as described later. This causes problems such as release of decomposed gas and precipitation of oligomer.

The surface of the heat-resistant film to be the surface of the support for a floppy disk is preferably as smooth as possible. This is because the surface property of the manufactured floppy disk has a very large effect on its electromagnetic conversion characteristics. Specifically, when an undercoat layer described below is used, the surface roughness measured by an optical surface roughness meter is 10 nm or less, preferably 5 nm or less in center line average roughness Ra, and is measured by a stylus roughness meter. The measured protrusion height is within 1 μm, preferably within 0.1 μm. When the undercoat layer is not used, the surface roughness measured by an optical surface roughness meter is 3 nm or less, preferably 1 nm or less in center line average roughness Ra, and the projection height measured by a stylus roughness meter is It is within 0.1 μm, preferably within 0.06 μm.

The adhesive surface of the heat-resistant resin film preferably has appropriate irregularities for handling and adhesiveness. Specifically, the surface roughness measured by an optical surface roughness meter is determined by the average of the center line. Roughness Ra within 10 nm, preferably 5 n
Within 0.1 m, protrusion height measured with a stylus type roughness meter is 0.1 μm
Within, preferably within 0.06 μm. Further, in order to further increase the adhesive strength, it is preferable to use an activation treatment of the adhesive surface. For the activation, generally known corona treatment, oxygen plasma treatment, flame treatment, ultraviolet treatment, ozone treatment, chromic acid treatment and the like can be used. Among them, corona treatment and oxygen plasma treatment are preferred from the viewpoint of the effect of improving adhesive strength and productivity.

Examples of the polyimide film include Upilex manufactured by Ube Industries, Ltd., Apical manufactured by Kanebuchi Chemical Co., Ltd.,
Examples include Kapton manufactured by Toray Dupont. Examples of the polyamide film include Aramica manufactured by Asahi Kasei Kogyo Co., Ltd. and Miktron manufactured by Toray Industries, Inc. The thickness of these heat resistant films is preferably in the range of 2 to 50 μm, particularly preferably 3 to 25 μm.

The thermoplastic resin film used in the present invention includes polyolefin, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyester, polyimide, polyetheretherketone, polyethersulfone, polyetherimide, polysulfone, polyphenylene sulfide, and tetrafluoroethylene. General resins such as fluorine resins selected from ethylene-hexafluoropropylene copolymer (FEP), alkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), and chlorotrifluoroethylene resin (CTFE) A suitable thermoplastic resin film can be used. Above all, the melting point is 200 ° C. to 300 from the viewpoint of adhesiveness.
Those in the range of ° C are preferred. If the melting point is higher than this, a high temperature is required for thermal bonding, and the productivity is reduced. Conversely, if the melting point is lower than this, the thermal stability of the floppy disk often decreases.

In selecting a heat-resistant resin film and a thermoplastic resin film, the following criteria are used. That is, in the present invention, in order to prevent the heat-resistant resin from adhering to the pressing member during the heat bonding, the melting point of the heat-resistant resin is higher than the heat bonding temperature, and the melting point of the thermoplastic resin is higher than the heat bonding temperature. Need to be low. Therefore, if a film is selected from such a viewpoint, for example, when bonding at 300 ° C., a combination using an aromatic polyimide for the heat-resistant resin film and polyether sulfone for the thermoplastic resin can be used. When bonding, use PF on heat-resistant resin
A can be used as a combination of A and polysulfone as a thermoplastic resin.

The thermoplastic resin film functions as an adhesive for the heat-resistant resin film, and the presence of the thermoplastic resin film on the support can reduce the warpage generated in the step of sputtering the magnetic layer. This is because even if warpage occurs in the heat-resistant resin film after the formation of the magnetic layer, the stress difference is caused by heating to a temperature equal to or higher than the glass transition point of the thermoplastic resin film during thermal bonding with the thermoplastic resin film. This is because it can be relaxed and fixed. In addition, it is possible to prevent warping in a specific direction due to the influence of temperature and humidity.

Since the thermoplastic resin film is used by melting and bonding by heating as described later, a general surface roughness can be used, but a smooth surface roughness is preferable. . Specifically, the surface roughness measured by an optical surface roughness meter is less than 10 nm in center line average roughness Ra,
The protrusion height is preferably within 5 nm, and the protrusion height measured with a stylus-type roughness meter is within 1 μm, preferably within 0.1 μm. This surface roughness is preferably substantially the same on the front and back surfaces.

The thermoplastic resin film of the present invention preferably has been subjected to a surface activation treatment in order to increase the adhesive strength. For the activation of the surface, generally known corona treatment, oxygen plasma treatment, flame treatment, ultraviolet treatment, ozone treatment, chromic acid treatment and the like can be used. Among them, corona treatment and oxygen plasma treatment are preferred from the viewpoint of the effect of improving adhesive strength and productivity. The thickness of this thermoplastic film is 3 to
It is 75 μm, preferably 5 to 50 μm.

According to the present invention, a laminate obtained by sandwiching a thermoplastic resin film between two heat-resistant resin films and heat-bonding the same is used as a support for a floppy disk. With such a film, the surface of the support can exhibit the excellent heat resistance of the heat-resistant resin film. In addition, heat bonding with one side of the heat-resistant resin film on the outside makes it possible to eliminate the warpage of each heat-resistant resin film, even if it is present. The occurrence of warpage in the direction can also be prevented. Furthermore, by setting the rough surface of the heat-resistant film to the inside, that is, the adhesive surface, and setting the smooth surface to the outside, that is, the surface, it is possible to obtain a support having both surfaces equal and smooth.

The thickness of the support of the present invention is 25 to 12
0 μm, preferably 30 to 75 μm. The optimum thickness of the support depends on the material of the film, the size of the floppy disk, and the recording / reproducing method of the floppy disk drive.

Next, a method for producing the floppy disk support of the present invention will be described. In the support for a floppy disk of the present invention, a thermoplastic resin film is sandwiched so that the surface of the heat-resistant resin film serving as the surface thereof is on the outside, and this is heated and bonded. As the heat bonding method, a method such as a flat plate hot press, a heat lamination using a heat laminating roll, a high-frequency bonding, and an ultrasonic bonding can be used. The heating temperature at this time is determined by the temperature required for bonding, but the bonding is preferably performed by heating to a temperature equal to or higher than the glass transition point of the thermoplastic resin film, more preferably equal to or higher than the melting point. When using a flat plate heat press, a heat-resistant resin film, a thermoplastic resin film, and a heat-resistant resin film may be laminated in this order and thermally bonded one by one, but a plurality of sheets may be laminated and pressed at once. Alternatively, the whole may be heated by a heating means such as an oven to perform the bonding.

Although these methods are inferior in productivity, since the heat and stress distribution on the front and back surfaces can be made uniform,
A support with less warpage can be produced, and a thermoplastic resin film having a high bonding temperature can be bonded. At this time, the press is preferably performed in a vacuum in order to prevent the generation of air bubbles on the bonding surface and to prevent dust from adhering to each film. The surface roughness of the pressed surface is preferably smoother than that of the support to be used. If the surface is rough, this surface is transferred to the support and the smoothness of the support surface is deteriorated. Further, the press surface is preferably subjected to surface processing such as fluorine processing in order to prevent sticking of the support after bonding. The pressing pressure is appropriate from 1 × 10 ^{−2 to} 1 MPa. The heating time depends on the thermal and chemical properties of the thermoplastic resin film, but is appropriately selected from several seconds to several hours.

When a heat laminating method using a heat laminating roll is used, a heat-resistant resin film, a thermoplastic resin film, and a heat-resistant resin film may be stacked in this order and adhered one by one to each sheet. You may laminate | stack continuously from roll to roll. When laminating in a single-wafer system, a film is placed on a smooth heating plate and bonded by pressing the film with a heat laminating roll or by passing the film between the heat laminating rolls. When laminating continuously, the film is adhered between the heat laminating rolls. The heating time at this time depends on the thermal and chemical properties of the thermoplastic resin film, but can be completed within several seconds.

For this reason, the surface temperature of the laminating roll often needs to be set higher than the bonding temperature of the thermoplastic resin film. As the heat laminating roll, general steam heating or heating with a heat medium oil can be used. In the case of a thermoplastic resin film having a high bonding temperature, an induction heating roll is used.

The surface property of the heat laminating roll is preferably smoother than that of the support to be used. If the surface is rough, the surface is transferred to the support, and the smoothness of the support surface is deteriorated. Further, the lamination is preferably performed in a vacuum in order to prevent generation of air bubbles on the bonding surface and to prevent dust from adhering to each film. The laminating roll pressure is suitably from 10 N / m to 10 kN / m.

A method of manufacturing a floppy disk using the floppy disk support of the present invention will be described below. When the surface properties of the heat-resistant resin film on the surface of the floppy disk support of the present invention are insufficient,
It is preferable to form an undercoat layer for the purpose of smoothing on the surface of the heat-resistant resin film. Since the undercoat layer is required to have heat resistance in the same manner as the heat-resistant resin film, it is necessary to use a polyimide resin, a polyamide-imide resin, a silicone resin, a fluorine-based resin or the like, and cannot use a polyester resin having a low heat resistance.

Among them, it is preferable to use a thermosetting imide or a thermosetting silicone resin having a high smoothing effect as a material of the undercoat layer. The thickness of the undercoat layer is preferably 0.1 to 3 μm. In addition, this undercoat layer was formed on the surface of the heat-resistant resin film before forming the support for the floppy disk, instead of applying the undercoat layer to the surface of the heat-resistant resin film on the surface of the support for the floppy disk. After that, it may be heated and bonded to the thermoplastic resin film. An example of using a thermosetting imide resin used as a substance for forming an undercoat layer is a polyimide resin which is a thermal polymer of an imide monomer having two or more terminal unsaturated groups in a molecule. An example of such an imide monomer is bisallylnadiimide represented by the following chemical formula 1.

◎

Embedded image

However, R ¹ and R ² are independently selected hydrogen or methyl groups, and R ³ is a divalent linking group such as an aliphatic or aromatic hydrocarbon group. That is, the thermosetting polyimide resin that is preferable as the base layer of the present invention is not a polyimide resin that has already been polymerized, but is a polyimide that is formed by first forming a coating film of an imide monomer on a heat-resistant resin film and then thermally polymerizing it.

This imide monomer has already undergone the imide cyclization reaction and has two or more terminal unsaturated groups in the molecule. The polymerization reaction on the polyimide proceeds by addition polymerization of the vinyl group by heating or the like. Therefore, since the polymerization reaction proceeds at a relatively low temperature, it can be formed as an underlayer on various non-magnetic supports including polyimide. Further, the imide monomer can be dissolved in a general-purpose organic solvent depending on its structure, and thus is excellent in productivity and workability. In addition, since the imide monomer has a smaller molecular weight than polyimide, the viscosity of the solution is low, and when this is applied on a non-magnetic support,
Good wraparound for unevenness and high smoothing effect. Such imide monomer compounds having an imide ring and two or more terminal unsaturated bonds are disclosed in JP-A-59-80662, JP-A-60-178882, and JP-A-61-18761.
JP-A-63-170358, JP-A-7-170358
A known compound synthesized by a known synthesis method described in 53516 and the like can be used.

In compound 1, R ¹ and R ² are each independently selected hydrogen or a methyl group, and R ³ may be any divalent linking group such as aliphatic or aromatic. it can. For example, a linear or branched alkylene group and alkenyl group, a cycloalkylene group, a cycloalkylene group having an alkylene group, an aromatic group, an aromatic group having an alkylene group, a polyoxyalkylene group, a carbonyl group, an ether group, and the like. No. The solvent solubility of the imide monomer and the heat resistance of the polyimide resin as a polymer thereof are mainly determined by the structure of R ³ . Thus the desired characteristics are achieved by selecting the structure of R ^3. As such compounds, those commercially available from Maruzen Petrochemical Co., Ltd. as BANI series and ANI series can be used.

The undercoat layer of the present invention may contain components other than imide monomers. For example, a curing agent for accelerating polymerization, heat-resistant fine particles (filler) for forming irregularities on the surface, a coupling agent for improving adhesion, a rust inhibitor for preventing oxidation of the magnetic layer, and the like are included. As a curing agent, p-toluenesulfonic acid, p-xylenesulfonic acid, methyl toluenesulfonate, pyridinium-p-toluenesulfonate, pyridinium-m-
Nitrobenzenesulfonate, methylhydrazine sulfate and the like can be used.

The coating solvent varies depending on the type of R ³ in Formula 1, but in many structures, toluene, xylene,
It is soluble in acetonitrile, cyclohexanone, methyl ethyl ketone, acetone, etc., and in some structures it is also soluble in isopropyl alcohol, ethanol, methanol, etc. These mixed solvents can be used as the solvent.

Further, as a preferred example of the thermosetting silicone resin in the present invention, a silicone resin prepared by a sol-gel method using a Keita compound into which an organic group has been introduced as a raw material may be mentioned. Such a silicone resin has a structure in which a part of the bond of silicon dioxide is substituted with an organic group, and has much higher heat resistance than silicone rubber. Further, since it is more flexible than a silicon dioxide film, cracking and peeling hardly occur even when it is formed on a flexible film such as a heat-resistant resin film.

Since the method is a method in which a monomer as a raw material is directly applied on a heat-resistant resin film and cured, a general-purpose solvent can be used, and wrapping around unevenness is good.
High smoothing effect. Furthermore, since the condensation polymerization reaction proceeds from a relatively low temperature by the addition of a catalyst such as an acid or a chelating agent, curing can be performed in a short time, and therefore, it can be produced by a general-purpose coating machine.

The monomer used as the raw material of the thermosetting silicone resin is a silane coupling agent having an organic residue such as an organic residue containing an aromatic hydrocarbon group, an aliphatic group or an epoxy group. Aromatic hydrocarbon groups and aliphatic hydrocarbon groups have the effect of imparting flexibility to the cured resin, and silane coupling agents having aromatic hydrocarbon groups are more heat-resistant than those having aliphatic hydrocarbon groups introduced. It is preferable because of excellent properties. Further, the silane coupling agent containing an epoxy group has an effect of curing the coating film from a relatively low temperature. For example, a silane coupling agent containing an aromatic hydrocarbon group is a compound having a structure represented by the following chemical formula 2.

◎

Embedded image

Wherein R and R 'are monovalent organic groups such as a methyl group; A is a divalent organic group such as a direct bond or an alkylene group;
B is a monovalent group x + y + z = 4 such as an alkoxy group, a halogen, and a hydroxyl group. In Chemical Formula 2, A is preferably absent, that is, directly connected or a methylene group. B is preferably an alkoxy group in consideration of reactivity and corrosiveness to the magnetic layer,
In order to facilitate the polymerization reaction, an alkoxy group having 4 or less carbon atoms such as a methoxy group is particularly preferable. x is preferably 1 or 2, but is particularly preferably 1 in order to facilitate the polymerization reaction. y is preferably 0 or 1, but particularly preferably 0 for facilitating the polymerization reaction. Accordingly, z is particularly preferably 3. Examples of such specific examples include the following.

◎

Embedded image

The silane coupling agent containing an organic residue having an epoxy group has, for example, a structure represented by the following chemical formula 3.

◎

Embedded image

A is a divalent organic residue such as an alkylene group B is a monovalent organic residue such as hydrogen or an alkyl group R is a monovalent organic residue such as an alkyl group X is an alkoxy group, a hydroxyl group, a halogen , A monovalent group selected from hydrogen, i + j + k = 4. In the structure of Formula 3, A is preferably hydrogen. R is a monovalent organic residue such as a methyl group or an ethyl group. X is preferably an alkoxy group in consideration of the reactivity and the influence on the corrosion of the magnetic layer. In order to facilitate the polymerization reaction, X is particularly preferably an alkoxy group having 4 or less carbon atoms such as a methoxy group. i is preferably 1 or 2, but is preferably 1 in order to facilitate the polymerization reaction. j is preferably 0 or 1, but particularly preferably 0 for facilitating the polymerization reaction. Therefore, k is particularly preferably 3. Examples of such a compound include those represented by the following chemical formula. These compounds are disclosed in JP-A-51-111871 and JP-A-61-18771.
It is described in JP-A-3-23224.

◎

Embedded image

For the purpose of heat resistance, cost reduction and polymerization rate adjustment, a silane coupling agent containing a hydrocarbon group such as a methyl group may be mixed and used. When a silane coupling agent containing a hydrocarbon is used in combination, the heat resistance of the undercoat layer can be improved. Specifically, this silane coupling agent containing a hydrocarbon group has the following structure. R—Si (OR ′) ₃ where R and R ′ are a hydrocarbon group, and the smaller the carbon number of R, the more effective the improvement of the heat resistance of the undercoat layer.

The portions of the silane coupling agent having an aromatic hydrocarbon group and the silane coupling agent containing an organic residue having an epoxy group, such as alkoxysilane, are hydrolyzed by coating and drying by the method described below.
Polymerizes to form siloxane bonds. On the other hand, the epoxy group undergoes ring opening polymerization by an acid catalyst or heat. The hydrolysis rate and the polymerization rate can be adjusted by adding an acid such as hydrochloric acid.

In order to start the polymerization from a lower temperature,
It is preferable to use a curing agent in combination, for example, a metal chelate compound,
Various compounds such as organic acids and salts thereof, and perchlorates are known, but a metal chelate compound is particularly preferred as a curing agent from the viewpoint of lowering the curing temperature and preventing corrosion of the magnetic layer. For example, when aluminum acetylacetonate is added to 3-glycidoxypropyltrimethoxysilane as a curing catalyst, curing can be performed only by heating at about 100 ° C. for a short time. Therefore, the film can be wound without blocking by using the gravure continuous coating method. As such a curing agent, a chelate compound of a metal with a β-diketone such as aluminum acetylacetonate, zirconium acetylacetonate, or titanium acetylacetonate is particularly effective. The coating solvent used at this time is determined by the amount of hydrochloric acid added and the structure of the silane coupling agent, but ethanol, methanol, isopropyl alcohol, cyclohexanone and the like can be used.

In the present invention, a method for preparing an undercoat layer comprising the above-mentioned thermosetting polyimide resin layer or thermosetting silicone resin layer on a heat-resistant resin film includes adding a monomer as a raw material and a curing agent if necessary. , A coating solution dissolved in an organic solvent, a wire bar method, a gravure method,
A method of applying the composition on a heat-resistant resin film by a method such as a spray method, a dip coating method, and a spin coating method and then drying the applied film can be used. Further, thereafter, the undercoat layer may be baked, if necessary, to accelerate the curing and improve heat resistance, solvent resistance, adhesion, and the like. Drying is performed to evaporate the solvent, but curing can be performed at this time. As a drying method, hot air drying, infrared drying and the like which are generally performed can be used. The drying temperature at this time is preferably about 60 ° C to 250 ° C.

After the coating film is dried, as a firing method for further accelerating the curing, hot air heating, infrared heating, hot roller heating and the like can be used. The heating temperature at this time depends on the thickness of the coating film, the method of forming the magnetic layer afterward, and the film forming temperature, but in the case of about 1 μm, it is in the range of 100 to 350 ° C., preferably 200 to 270 ° C. It is. If the temperature is lower than this, the progress of the polymerization reaction may be insufficient, or a residual gas or a decomposition gas may be generated during the sputtering of the magnetic layer, which may hinder the crystal growth of the magnetic layer. Conversely, if it is too high, the support may be deformed or productivity may be reduced. For some materials, polymerization by ultraviolet irradiation, electron beam irradiation, or the like is also possible in addition to polymerization by heating.

Further, by providing very small projections on the surface of the undercoat layer, the real contact area between the magnetic recording medium and the sliding member can be reduced, and the sliding characteristics can be improved. It is particularly preferable that the surface of the magnetic layer on the material has a fine projection structure. This microprojection structure has the effect of significantly improving the handleability of the support after bonding. As a method of producing such a fine projection structure, a method of applying spherical silica particles, a method of applying an emulsion to form organic projections, and the like can be used, but silica particles are preferable in order to ensure heat resistance.

It is also possible to use a binder to fix the projections to the film surface, but it is preferable to use a resin having sufficient heat resistance in order to secure the heat resistance. It is particularly preferable to use a thermosetting imide or a thermosetting silicone resin used for forming a layer. The height of the microprojections is 5 to 60 nm, preferably 10 to 30 nm, and the density is 0.1 to 100.
Particles / μm ² , preferably 1 to 10 particles / μm ² . If the height of the minute projections is too high, the electromagnetic conversion characteristics are degraded due to the spacing loss between the recording / reproducing head and the medium. If the height of the minute projections is too low, the effect of improving the sliding characteristics is reduced. If the density of the fine projections is too low, the effect of improving the sliding characteristics is reduced, and if it is too high, the number of high projections increases due to the increase in aggregated particles, and the electromagnetic conversion characteristics deteriorate. The coating thickness of the binder is 20 nm or less. If the binder is too thick, it may adhere (block) to the back surface of the film after drying.

The ferromagnetic metal thin film serving as a magnetic layer in the floppy disk of the present invention is formed by a sputtering method or a vacuum evaporation method. Examples of the composition of the magnetic layer include metals or alloys mainly containing cobalt.
o-Cr, Co-Ni-Cr, Co-Cr-Ta, Co
-Cr-Pt, Co-Cr-Ta-Pt, Co-Cr-
Pt-Si, Co-Cr-Pt-B, Co-O or the like can be used. In particular, Co-Cr is used to improve electromagnetic conversion characteristics.
-Pt and Co-Cr-Pt-Ta are preferred. It is desirable that the thickness of the magnetic layer be 10 to 30 nm.

In this case, it is preferable to provide an underlayer for improving the magnetostatic property of the magnetic layer. The composition of the underlayer may be a metal or an alloy. Specifically, Cr, V, Ti , Ta, W, Si and the like or alloys thereof can be used. Among them, Ta, Ni-P, Ni-A
1, Cr-Ti is particularly preferred. The thickness of the underlayer is 5 nm to 50 nm, preferably 10 nm to 3 nm.
0 nm.

In order to further control the crystal orientation of the underlayer, it is preferable to use a seed layer under the underlayer. Specifically, Ta, Mo, W, V, Zr, Cr, Rh, H
f, Nb, Mn, Ni, Al, Ru, Ti or an alloy thereof, particularly preferably Ta, Cr, Ti or an alloy thereof, and preferably has a thickness of 15 to 60 nm. Also, these are used in an amorphous state or in a state where the crystallite is smaller than that of the underlayer, unlike the underlayer.

Further, an adhesion layer may be formed in order to enhance the adhesion between the undercoat layer and the seed layer. If the seed layer is not formed, the adhesion between the undercoat layer and the underlayer may be increased. An adhesion layer may be introduced. As the adhesion layer, specifically, Cr, V, Ti, Ta, W, Si, or the like or an alloy thereof can be used. When the magnetic layer is formed by a sputtering method, it is preferable to form a film while the support is heated, and it is preferable to use a DC or RF magnetron sputtering method and set the temperature of the support to 100 ° C. to 250 ° C.

On the other hand, it is necessary to be careful that the temperature of the support is not only heated but also heated by sputtering. In addition, both the sputtering method and the vacuum deposition method can be used, either a single-wafer type film forming method for forming a film one by one or a web film forming method for continuously forming a film on a web-like film. When performance is important, a single-wafer type film forming method is preferable, and when productivity is important, a web film forming method is preferable. In particular, when the present invention is used in the web film forming method, the productivity can be significantly improved. This is because the formation of the magnetic layer only needs to be performed on one side in the web film formation method. This is because surface defects can be significantly reduced, and continuous lamination using a hot laminator roll can be performed for bonding.

In the floppy disk of the present invention, it is preferable to provide a protective layer on the ferromagnetic metal thin film, and this protective layer can significantly improve running durability and corrosion resistance. As the protective layer, silica, alumina, titania, zirconia, cobalt oxide, oxides such as nickel oxide, nitrides such as titanium nitride, silicon nitride, boron nitride, silicon carbide, chromium carbide, carbides such as boron carbide,
Examples of the protective layer include carbon such as graphite and amorphous carbon. As this protective layer, a hard film having a hardness equal to or higher than that of the head material is preferable, and further, a material that hardly causes seizure during sliding and has a stable and stable effect is most preferable. Examples include a hard carbon film called diamond-like carbon (DLC).

The diamond-like carbon film is formed by plasma CVD.
Law, an amorphous carbon film produced by sputtering, cluster and Sp by microscopically Sp ² bond
It is a mixture of clusters by ^three bonds. The hardness of this film is 10 × 10 ² MPa to 20 × 10 ^{3 in} Vickers hardness.
MPa or more. When measured by Raman spectroscopy of the diamond-like carbon film, a main peak called a G peak at about 1540 ^-1 cm was 139.
This can be confirmed by detecting a so-called D peak at 0 cm ^-1 . These diamond-like carbon films can be prepared by a sputtering method or a CVD method. However, since the productivity, the stability of quality, and the excellent abrasion resistance can be ensured even with an ultrathin film having a thickness of 10 nm or less, the CVD method is used. It is preferable to produce the methane, ethane,
Negative bias voltage is applied to the magnetic layer or a reticulated electrode provided in front of the magnetic layer by decomposing a carbon-containing compound such as an alkane such as propane or butane, an alkene such as ethylene or propylene, or an alkyne such as acetylene. It is preferable to apply the pressure and accelerate the deposition.

Further, nitrogen gas is mixed with the raw material gas, and C,
By using a diamond-like carbon film made of H and N, the coefficient of friction with respect to the head can be reduced. When the thickness of the hard carbon protective layer is large, the electromagnetic conversion characteristics are deteriorated and the adhesion to the magnetic layer is reduced, and when the thickness is small, the wear resistance is insufficient. Preferably 5
20 nm.

In the floppy disk 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 layer or the protective layer. As the lubricant, known hydrocarbon-based lubricants, fluorine-based lubricants, extreme pressure additives and the like 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 a part or all of the alkyl group of the hydrocarbon-based lubricant is replaced 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 ) CF
₂ O) _n or a copolymer thereof. Specifically, a perfluoromethylene-perfluoroethylene copolymer having a hydroxyl group at a molecular weight terminal (FODI manufactured by Audimont Co., Ltd.)
MBLIN Z-DOL).

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 layer or protective layer.
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^TwoIs particularly preferred.

Examples of the rust preventive usable in the present invention include nitrogen-containing heterocycles such as benzotriazole, benzimidazole, purine and pyrimidine, derivatives having an alkyl side chain or the like introduced into their mother nucleus, benzothiazole, 2-mercapto And nitrogen- and sulfur-containing heterocycles such as benzothiazole, tetrazaindene ring compounds and thiouracil compounds, and derivatives thereof. These may be mixed with a lubricant and applied on the protective layer, or may be applied on the protective layer before applying the lubricant, and the lubricant may be applied thereon. The coating amount of the rust inhibitor is 0.1 to 10 mg / m ^2.
Is preferable, and 0.5 to 5 mg / m ² is particularly preferable. Tetrasignedene ring compounds usable for such purposes include those shown below.

◎

Embedded image

Here, R is a hydrocarbon group selected from an alkyl group, an alkoxy group and an alkylamide group.
Particularly preferably not having 3 to 20 carbon atoms, R ⁴ OCOCH ₂ in the case of alkoxy - R ⁴ s, C ₃ H
_{7 -, C 6 H 13 -} , phenyl, also in the case of alkyl _{groups, C 6 H 13 -, C} 9 H 19 -, C 17 H 35 - , and the like, in the case of an alkylamide R ⁵ NHCOCH ₂ - the R ⁵ phenyl, C ₃ H ₇ - and the like. Further, examples of the thiouracil ring compound include the following.

◎

Embedded image

Here, R is selected from the same as those in the above-mentioned tetrazaindene ring compound.

[0075]

The present invention will be described below with reference to examples. Example 1 A mirror-polished stainless steel plate having a diameter of 20 cm was subjected to corona treatment on the rough surface side, the maximum protrusion roughness R _{max of} the smooth surface was 0.1 μm, the average center line roughness Ra was 1.2 nm, and the thickness was 1
A circular aromatic polyamide film having a diameter of 2 μm and a diameter of 18 cm is spread so that a smooth surface is a lower surface, and an average center line roughness Ra of the surface is 4.1 nm, a thickness is 25 μm, and a diameter is 1 μm.
A 6 cm circular polyetherimide film was overlaid, and the aromatic polyamide film was further overlaid thereon such that the smooth surface was on the upper surface. This is a set, and this is 10
The assembled and mirror-polished stainless steel plates having a diameter of 20 cm were pressed in a vacuum while applying a pressure of 981 Pa. Take it out to the atmosphere in this state, place it in an oven,
Heat at 0 ° C. for 5 hours. Thereafter, the film was taken out to produce a floppy disk support 1A.

Next, this floppy disk support 1
A surface of thermosetting imide resin (BA manufactured by Maruzen Petrochemical Co., Ltd.)
A solution of NI-NB) in a mixed solvent of cyclohexane / ethanol (1: 1) was applied by dip coating, dried at room temperature, and then heated at 250 ° C. for 3 hours to produce a 1.0 μm thick undercoat layer. . Furthermore, a silica particle having an average diameter of 25 nm and a solution of a thermosetting imide resin in cyclohexanone are applied thereon, and then dried at 250 ° C. for 1 hour. The average value of the projection height is 20 nm and the projection density is 3
A microprojection of μm ² was formed. This was designated as support 1B.

Next, the support 1B is cut out, sandwiched and fixed in a circular holder to which a uniform tension is applied.
After being set in a sputtering apparatus for forming a magnetic layer and heating the support to 200 ° C., a 30 nm Cr-Ti underlayer was formed by DC magnetron sputtering, followed by a 30 nm Co-Cr-Pt magnetic layer. did. The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out of the sputtering apparatus, and a 15-nm-thick diamond-like carbon protective film was formed on the magnetic layer by a plasma CVD method using ethane as a raw material.

Next, the sample is taken out of the holder,
A solution of a perfluoropolyether-based lubricant (FOMBLINZ-DOL manufactured by Ausimont) in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M) is applied on the protective layer by dip coating to form a lubricating layer having a thickness of 1 nm. Was prepared. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD1. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 2 A corona-treated rough surface side of a mirror-polished stainless steel plate having a diameter of 20 cm, the maximum protrusion roughness R _{max of} the smooth surface was 0.2 μm, the average center line roughness Ra was 2.0 nm, Thickness 2
A circular aromatic polyimide film having a diameter of 5 μm and a diameter of 18 cm is spread so that a smooth surface is a lower surface, and an average center line roughness Ra of the surface is 5.5 nm, a thickness is 25 μm, and a diameter is 1 μm.
A film made of tetrafluoroethylene-ethylene copolymer (ETFE) having a circular surface of 6 cm whose activation treatment was performed was overlaid, and the above-mentioned aromatic polyimide film was further overlaid thereon such that the smooth surface became the upper surface. This is one set,
10 sets of these are mirror-polished in a vacuum of 20 cm in diameter.
Was pressed while applying a pressure of 981 Pa to the stainless steel plate. In this state, it was taken out into the atmosphere, placed in an oven, and heated at 290 ° C. for 5 hours. Thereafter, the film was taken out and used as a support 2A.

Next, a solution of a thermosetting imide resin (BANI-NB manufactured by Maruzen Petrochemical Co., Ltd.) in a cyclohexane / ethanol mixed solvent (1: 1) was applied to the surface of the support 2A by dip coating. After drying at room temperature, 25
The mixture was heated at 0 ° C. for 3 hours to form a 1.7 μm-thick undercoat layer. Furthermore, after applying a cyclohexanone solution of silica particles having a diameter of 25 nm and a thermosetting imide resin thereon,
After drying at 250 ° C. for 1 hour, the average height of the protrusions is about 20.
Nano-projections having a thickness of 3 nm / μm ² were formed.
This was designated as support 2B. Next, the support 2B was cut out, sandwiched and fixed in a circular holder to which a uniform tension was applied, installed in a sputtering apparatus for forming a magnetic layer, and heated to 200 ° C., and then Cr was applied by DC magnetron sputtering. -Forming a Ti underlayer of 30 nm, and further forming a Co-Cr-Pt magnetic layer of 30 nm
A film was formed.

The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out of the sputtering apparatus, and a plasma CV using ethane as a raw material was formed on the magnetic layer.
A diamond-like carbon protective layer having a thickness of 15 nm was formed by Method D. Next, the sample was taken out of the holder, and a solution prepared by dissolving a perfluoropolyether-based lubricant (FOMBLINZ-DOL manufactured by Ausimont) in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M) on the protective layer was subjected to dip coating. To form a lubricating layer having a thickness of 1 nm. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD2. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

[0082] Example 3 matte side on a stainless steel plate of mirror-polished 20cm in diameter has been corona treated, maximum protrusion roughness R _max of the smooth surface is 0.1 [mu] m, an average center line roughness Ra of 1.2 nm, Thickness 2
A circular aromatic polyamide film having a diameter of 5 μm and a diameter of 18 cm is spread so that a smooth surface is a lower surface, and an average center line roughness Ra of the surface is 4.1 nm, a thickness is 25 μm, and a diameter is 1
Overlay 6cm circular polyethersulfone film,
Further, the aromatic polyamide film was further laminated thereon such that the smooth surface became the upper surface. This is a set, and this is 1
0 sets were stacked and pressed while applying a pressure of 981 Pa to a stainless steel plate having a diameter of 20 cm and mirror-polished in vacuum. Take it out to the atmosphere in this state, place it in an oven,
Heat at 60 ° C. for 5 hours. Thereafter, the film was taken out and used as a support 3A.

Next, a thermosetting silicone resin having the following composition was applied to the surface of the support 3A by dip coating, dried at room temperature, and then heated at 250 ° C. for 3 hours to form a film having a thickness of 0.5
A μm undercoat layer was prepared. Furthermore, on top of this, a diameter of 25n
m of silica particles and an ethanol / cyclohexanone solution (1: 1) of the following thermosetting silicone resin, followed by drying at 250 ° C. for 1 hour to obtain an average protrusion height of 2
Fine projections having a thickness of 0 nm and a projection density of 3 / μm ² were formed. This was designated as support 3B.

3-glycidoxypropyltrimethoxysilane 20.0% by weight Phenyltriethoxysilane 20.0% by weight Ethanol 44.6% by weight Cyclohexanone 0.6% by weight Purified water 10.0% by weight Hydrochloric acid (1 mol / l) 4.4% by weight Aluminum acetylacetonate 0.4% by weight Next, the support 3B was cut out, sandwiched and fixed in a circular holder to apply a uniform tension, and set in a sputtering apparatus for forming a magnetic layer. After the support was heated to 200 ° C, Cr-T was applied by DC magnetron sputtering.
i An underlayer is formed to a thickness of 30 nm, and further Co-Cr
-A 30 nm thick Pt magnetic layer was formed.

The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out from the sputtering apparatus, and a plasma CV using ethane as a raw material was formed on the magnetic film.
A diamond-like carbon protective layer having a thickness of 15 nm was formed by Method D. Next, the sample was taken out of the holder, and a solution prepared by dissolving a perfluoropolyether-based lubricant (FOMBLINZ-DOL manufactured by Ausimont) in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M) on the protective layer was subjected to dip coating. To form a lubricating layer having a thickness of 1 nm. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD3. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

Example 4 A mirror-polished stainless steel plate was subjected to corona treatment on the rough surface side, the maximum roughness R _{max of} the smooth surface was 0.2 μm, the average center line roughness Ra was 2.0 nm, the thickness was 25 μm, 20c
A square m-sided aromatic polyimide film is spread so that the smooth surface is the lower surface, and the center line average roughness R
a is a 4.5 mm thick, 25 μm thick, 16 cm square film made of chlorotrifluoroethylene resin (CTFE) having an activated surface, and the aromatic film is further superposed thereon such that the smooth surface becomes the upper surface. A polyimide film was overlaid. This is a set, and the roll temperature is 30 in vacuum.
Laminating rolls at 0 ° C. were run at a speed of 0.1 m / sec while applying a linear pressure of 491 N / m to perform lamination.
This was taken out into the atmosphere and used as a support 4A.

Next, a solution of a thermosetting imide resin (BANI-NB manufactured by Maruzen Petrochemical Co., Ltd.) in a cyclohexane / ethanol mixed solvent (1: 1) was applied to the surface of the support 4A by dip coating. After drying at room temperature, 25
The mixture was heated at 0 ° C. for 3 hours to form a 1.7 μm-thick undercoat layer. Further, a solution of silica particles having an average diameter of 25 nm and a solution of a thermosetting imide resin in cyclohexanone was applied thereto, and then dried at 25.0 ° C. for 1 hour. / Μm ² . This was designated as support 4B. Next, the support 4B was cut out, sandwiched and fixed in a circular holder to which a uniform tension was applied, installed in a sputtering apparatus for forming a magnetic layer, heated to 200 ° C., and then subjected to DC magnetron sputtering. -Forming a Ti underlayer of 30 nm, and further forming a Co-Cr-Pt magnetic layer of 30 nm
A film was formed.

The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out of the sputtering apparatus, and a plasma CV using ethane as a raw material was formed on the magnetic layer.
A diamond-like carbon protective layer having a thickness of 15 nm was formed by Method D. Next, the sample was taken out of the holder, and a solution prepared by dissolving a perfluoropolyether-based lubricant (FOMBLINZ-DOL manufactured by Ausimont) in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M) on the protective layer was subjected to dip coating. To form a lubricating layer having a thickness of 1 nm. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD4. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

[0089] Comparative Example 1 roughened surface are corona treated, maximum protrusion roughness R _max is 0.2μm smooth surface, the average center line roughness Ra of 2.0 nm, roughness of the polyimide film having a thickness of 25μm An N, N-dimethylacetamide solution of a thermosetting polyimide resin (CT4112 manufactured by Toshiba Chemical Co., Ltd.) was applied as a bonding agent to the surface side by a spray method, and dried at 120 ° C. for 30 minutes. After cutting this polyimide film into a square of 20 cm square, it is spread on a mirror-polished stainless steel plate so that the smooth surface is the lower surface, and the average center line roughness Ra of the surface is 4.5 nm, the thickness is 25 μm, A film of chlorotrifluoroethylene (CTFE) having a square surface of 16 cm square and activated was overlaid, and the above-mentioned aromatic polyimide film was further overlaid thereon such that the smooth surface became the upper surface. This is a set, roll temperature is 300 ℃ in vacuum
Was applied at a speed of 0.1 m / sec while applying a linear pressure of 491 N / m to perform lamination. This was taken out into the atmosphere and used as a support 5A.

Next, a solution of a thermosetting imide resin (BANI-NB manufactured by Maruzen Petrochemical Co., Ltd.) in a cyclohexane / ethanol mixed solvent (1: 1) was applied to the surface of the support 5A by dip coating. After drying at room temperature, 25
The mixture was heated at 0 ° C. for 3 hours to form a 1.7 μm-thick undercoat layer. Furthermore, a silica particle having an average diameter of 25 nm and a cyclohexanone solution of a thermosetting imide resin were applied thereon, followed by drying at 250 ° C. for 1 hour.
Fine projections having a thickness of 0 nm and a projection density of 3 / μm ² were formed. This was designated as support 5B. Next, the support 5B was cut out, sandwiched and fixed in a circular holder to which a uniform tension was applied, installed in a sputtering apparatus for forming a magnetic layer, and after heating the support to 200 ° C., Cr was applied by DC magnetron sputtering. -Forming a 30 nm Ti underlayer, and further forming a 30 nm Co-Cr-Pt magnetic layer
A film was formed.

The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out of the sputtering apparatus, and a plasma CV using ethane as a raw material was formed on the magnetic layer.
A diamond-like carbon protective layer having a thickness of 15 nm was formed by Method D. Next, the sample was taken out of the holder, and a solution prepared by dissolving a perfluoropolyether-based lubricant (FOMBLINZ-DOL manufactured by Ausimont) in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M) on the protective layer was subjected to dip coating. To form a lubricating layer having a thickness of 1 nm. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD5. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

[0092] Comparative Example 2 the maximum protrusion roughness R _max is 0.1μm smooth surface, the center line average roughness Ra 1.2 nm, the rough surface R _max is 0.2 [mu] m, R
The support 6A is a circular aromatic polyamide film having the same chemical structure as that of Example 1 having a diameter of 1.8 nm, a thickness of 50 μm, and a diameter of 18 cm, and a thermosetting imide resin (Maruzen Petrochemical Co., Ltd.) A solution of BANI-NB) in cyclohexane / ethanol mixed solvent was applied by dip coating, dried at room temperature, and heated at 250 ° C. for 3 hours to form a 1.0 μm thick undercoat layer. Further, a cyclohexanone solution of silica particles having an average diameter of 25 nm and a thermosetting imide resin was applied thereon,
After drying at 50 ° C. for 1 hour, the average height of the protrusions is 20 n.
m, microprojections having a projection density of 3 / μm ² were formed. This was designated as support 6B.

Next, the support 6B was cut out, sandwiched and fixed in a circular holder to which a uniform tension was applied, and set in a sputtering apparatus for forming a magnetic layer.
After heating to 00 ° C., a 30 nm Cr-Ti underlayer was formed by DC magnetron sputtering, followed by a 30 nm Co-Cr-Pt magnetic layer. The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out from the sputtering apparatus, and the thickness of the magnetic layer was reduced to 1 by a plasma CVD method using ethane as a raw material.
A 5 nm diamond-like carbon protective layer was formed. Next, the sample was taken out of the holder, and a perfluoropolyether-based lubricant (FOM manufactured by Ausimont, Inc.) was placed on the protective layer.
A solution of BLINZ-DOL in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M Limited) was applied by a dip coating method to form a lubricating layer having a thickness of 1 nm. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD6. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

[0094] Comparative Example 3 smooth surface maximum protrusion roughness R _max is 0.2 [mu] m, the average center line roughness Ra of 2.0 nm, R _max of the rough surface is 0.2 [mu] m, R
a is a circular aromatic polyimide film having a thickness of 2.9 μm, a thickness of 50 μm, and a diameter of 18 cm is used as a support 7A, and then a thermosetting imide resin (BANI-NB manufactured by Maruzen Petrochemical Co.) is formed on the surface of the support 1. A solution dissolved in a mixed solvent of cyclohexane / ethanol was applied by a dip coating method, dried at room temperature, and then heated at 250 ° C. for 3 hours to have a thickness of 1.7 μm.
m undercoat layer was formed. On top of this, an average diameter of 25
After applying a cyclohexanone solution of silica particles and a thermosetting imide resin having a thickness of 10 nm, the coating was dried at 250 ° C. for 1 hour to form minute projections having an average projection height of 20 nm and a projection density of 3 / μm ² . . This was designated as support 7B.

Next, the support 7B was cut out, sandwiched and fixed in a circular holder to which a uniform tension was applied, and set in a sputtering apparatus for forming a magnetic layer.
After heating to 00 ° C., a 30 nm Cr-Ti underlayer was formed by DC magnetron sputtering, followed by a 30 nm Co-Cr-Pt magnetic layer. The underlayer and the magnetic layer were formed on both sides of the support. Further, this sample was taken out from the sputtering apparatus, and the thickness of the magnetic layer was reduced to 1 by a plasma CVD method using ethane as a raw material.
A 5 nm diamond-like carbon protective layer was formed. Next, the sample was taken out of the holder, and a perfluoropolyether-based lubricant (FOM manufactured by Ausimont, Inc.) was placed on the protective layer.
A solution of BLINZ-DOL in a fluorine-based solvent (FC-77 manufactured by Sumitomo 3M Limited) was applied by a dip coating method to form a lubricating layer having a thickness of 1 nm. Then, the sample was punched into a 3.5-type magnetic disk to produce a floppy disk. This sample was designated as FD7. The obtained floppy disk support and floppy disk were evaluated by the following evaluation methods, and the results are shown in Table 1.

(Evaluation Method) (1) Appearance The floppy disk support and the floppy disk of each example were visually observed and observed with an optical microscope.
00 times), and the presence of foreign matter on the surface of the support and the adhesive surface and the occurrence of bubbles were examined. (2) Adhesiveness A floppy disk was cut into a square of 5 mm square, and a polyester adhesive tape (Nitto Denko # 31) was cut from both sides.
B) was affixed, and when the adhesive tape was peeled off, the presence or absence of peeling at the lamination interface of the floppy disk support was examined. (3) Curl value The floppy disk support and the completed floppy disk are punched into a 3.5-type floppy disk shape, and the disks are rotated vertically at 60 rpm with the disk center being chucked by a ring in a state of standing vertically. Was.
And in the radial direction, a radial position from the inner circumference of 20 mm
Scan the area of 45mm with laser displacement meter and
The difference between the position where the distance between the displacement gauges was the shortest and the position where the distance was the longest was determined and defined as a curl value.

[0097]

Table 1 Sample Appearance Adhesion Curl (mm) Example 1 Support 1A Good 0.5 Good Support 1B Good 0.4 Good FD1 Good Good 0.9 Good Example 2 Support 2A Good 0.2 Good Support Body 2B Good 0.3 Good FD2 Good Good 0.5 Good Example 3 Support 3A Good 0.4 Good Support 3B Good 0.4 Good FD3 Good Good 0.6 Good Example 4 Support 4A Good 0.8 Good Support 4B Good 0.9 Good FD4 Good Good 1.0 Good Comparative Example 1 Support 5A Bubble, foreign matter, undulation 2.1 Good Support 5B Bubble, foreign matter, undulation 2.5 Good FD5 Bubble, foreign matter, undulation Good 3.5 good Comparative example 2 support 6A good 2.5 good support 6B good 2.6 good FD6 good good 3.8 good Comparative example 3 support 7A good 1.4 good support 7B good 1.5 Good FD7 good good good 2.0

As described above, the floppy disk support and the floppy disk produced according to the present invention were all excellent in appearance, adhesiveness and curl amount. On the other hand, in Comparative Example 1 in which a thermosetting polyimide resin was used as the adhesive for the production of the laminate, bubbles thought to be due to the residual solvent were generated, and deformation of the medium due to foreign matter caught on the bonding surface was observed in some places. Was. In addition, undulation was observed on the support 5A due to shrinkage due to curing. Further, in Comparative Examples 2 and 3 in which one film was used as a support without lamination, the warpage inherent to the film remained, and the curl amount increased.

[0099]

According to the present invention, it is possible to produce a support having a small amount of warpage and a small number of defects on the surface and the bonding surface, and a floppy disk produced using this support also has a small curl amount. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a floppy disk support of the present invention.

FIG. 2 is a sectional view illustrating a floppy disk of the present invention.

[Explanation of symbols]

1A: Floppy disk support, 1B: Floppy disk, 2 ... Thermoplastic resin film, 3 ... Magnetic layer, 4
... heat-resistant resin film, 5 ... undercoat layer, 6 ... underlayer, 7
... magnetic layer, 8 ... seed layer, 9 ... adhesion layer, 10 ... protective layer,
11: Lubrication layer

Claims (8)

[Claims] 1. A floppy disk support, comprising:
A support for a floppy disk, wherein the support comprises a heat-resistant resin film bonded to both surfaces of a thermoplastic resin film by heating. 2. The floppy disk according to claim 1, wherein the heat-resistant resin films present on both sides of the support are selected from aromatic polyamide films and aromatic polyimide films. Support. 3. The floppy according to claim 1, wherein the thermoplastic resin film is selected from the group consisting of polyetherimide, polyethersulfone, polysulfone, polyetheretherketone, fluororesin, and polyimide. Support for disk. 4. The floppy disk support according to claim 1, wherein an undercoat layer is provided on both sides of the surface of the heat-resistant resin film and subjected to a smoothing treatment. 5. The support for a floppy disk according to claim 4, wherein the undercoat layer is one of a thermosetting polyimide and a thermosetting silicone resin. 6. A method for producing a floppy disk, comprising: forming a magnetic layer and a protective layer on the floppy disk support according to claim 1. 7. A method of manufacturing a support for a floppy disk, comprising: laminating a heat-resistant resin film on both surfaces of a thermoplastic resin film; pressing the plate with a flat plate; A method for producing a support. 8. A method for manufacturing a support for a floppy disk, comprising: laminating a heat-resistant resin film on both surfaces of a thermoplastic resin film; heating and pressing with a heating roller; A method for producing a support.