JP2000228012A - Production of floppy disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure superior electromagnetic transducing characteristics and traveling durability by forming a thermosetting imide-containing adhesive layer on the surface of one of heat resistant films, sticking the films together by dry laminating, forming a magnetic film on the resulting substrate and providing a prescribed shape. SOLUTION: When two or more heat resistant films such as polyimide films or polyamide films are stuck together to form a nonmagnetic substrate, a thermosetting imide resin adhesive layer is formed on the surface of one of the heat resistant films and the films are stuck together by dry laminating. The thermosetting imide is soluble in many ordinary solvents, a solution of the thermosetting imide is readily dried and bubbles are hardly generated after adhesion. Since the solution has low viscosity and can be micro-filtered, the inclusion of foreign matter is suppressed. The objective substrate having a smooth surface property and high heat resistance, less liable to warp and having high dimensional precision is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In a magnetic recording medium such as a magnetic tape or a hard disk, a magnetic recording medium such as a vapor-deposited tape or a thin-film hard disk having a recording layer of a ferromagnetic metal thin film produced by a vacuum film forming method such as a sputtering method or a vapor-deposition method. The medium has been put to practical use. In such a magnetic recording medium, high magnetic energy can be easily obtained, and smooth surface properties can be easily achieved by smoothing the surface of the non-magnetic substrate. Because of its characteristics, it is suitable for high-density recording materials. 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, a floppy disk type magnetic recording medium is very widely used because of its excellent impact resistance and low cost as compared with a bird disk. Further, the applicant of the present invention has proposed a 3.5-inch 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 many attempts to produce a magnetic film by a sputtering method like a hard disk have been reported, but have 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 following four characteristics are required for the support of a floppy disk for producing a magnetic film by a sputtering method. (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 A magnetic film for high-density recording requires electromagnetic conversion characteristics such as high output and low noise. For this reason, when a magnetic film is produced by a sputtering method, a film is formed while heating a 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 occur due to a difference in stress between the front and back sides in the process of manufacturing the medium, when the support originally has it. The warpage generated in the manufacturing process can be adjusted by the process conditions, but the warpage that the support originally has is very difficult to adjust by the process conditions because the thickness of the support is much larger than the thickness of the magnetic film. 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, 1 mm is punched into a 3.5 inch disk shape.
It is necessary to hold down below.

(4) Dimensional stability Recent floppy disks are considered to be used inside notebook computers due to the spread of notebook computers. However, the temperature inside the notebook computers is high, and the notebook computers are out of the office. It is often used in a wide range of temperatures. Under such circumstances, the floppy disk must have excellent dimensional stability with respect to temperature and be capable of stable tracking. For this purpose, the support must be thermally excellent in dimensional stability. It is very difficult to develop a support that satisfies the above four necessary 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 a heating temperature when a magnetic film is formed by a sputtering method. Therefore, deformation occurs when the magnetic film is formed, and cracks often occur in the magnetic film.
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 films such as polyimide and polyamide have sufficient heat resistance, it is difficult to realize smooth surface properties and low warpage due to problems in their production. The polyamide film is 50μ
It is difficult to produce a film having a thickness of m or more. 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.

Therefore, in order to produce a support which satisfies the above-mentioned required properties, it is necessary to process an existing film to improve the properties as a 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 if the film has a warp, the warp can be significantly reduced by laminating the warp in a direction in which the warp cancels 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, in the conventional method of laminating using a general-purpose epoxy-based adhesive, the heat resistance of the adhesive is insufficient because the adhesive has insufficient heat resistance. There was a problem. 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 has been a problem that bubbles are generated on the bonding surface in the thermosetting process for bonding. Furthermore, when using other thermosetting or thermoplastic resins with high heat resistance as an adhesive, the viscosity of the adhesive is so high that it is not possible to remove foreign substances by precise filtration of the adhesive. There is a problem that foreign matter is easily mixed.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method for bonding a heat-resistant film such as a polyimide film or a polyamide film by a dry lamination method using a specific adhesive to obtain a smooth surface, high heat resistance, low warpage, An object of the present invention is to prepare a support having high dimensional stability and to provide a floppy disk medium suitable for high-density recording.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a floppy disk medium having a magnetic film on at least one surface of a non-magnetic support on which at least two heat-resistant films are laminated. This is a method for manufacturing a floppy disk having a predetermined shape after forming a magnetic layer on a support bonded by dry lamination after forming an adhesive layer containing a thermosetting imide.
Further, in the above-mentioned method for producing a floppy disk, the heat-resistant film is selected from a polyamide film and a polyimide film.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyimide film,
In a method for manufacturing a floppy disk medium having a magnetic film on at least one of non-magnetic supports obtained by laminating two or more heat-resistant films such as polyamide films,
It has been found that the problem can be solved by a method of manufacturing a floppy disk medium, which is characterized by laminating by a dry lamination method using an adhesive having a thermosetting imide resin layer formed into a heat-resistant film.

The thermosetting imide used in the present invention refers to a monomer having an imide structure and a polymerizable terminal group in the molecule. This monomer is polymerized by heating to form a polyimide structure, and thus has excellent adhesive strength at high temperatures. Since this thermoplastic imide is in a monomer state before bonding, it can be dissolved in many types of solvents and is soluble in many common solvents.
For this reason, drying of the solvent is easy, and generation of bubbles after bonding is small. Further, since this solution has a low viscosity and can be subjected to precise filtration, foreign matter is not easily mixed. By using a thermosetting imide having such excellent characteristics as an adhesive, a support having smooth surface properties, high heat resistance, low warpage, and high dimensional stability is produced, and is suitable for high-density recording. A floppy disk medium can be provided. As such a thermosetting imide, for example, bisallylnadiimide represented by the following chemical formula 1 is particularly effective.

[0015]

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R ¹ and R ² are independently selected hydrogen or a methyl group, and R ³ is a divalent linking group such as an aliphatic or aromatic hydrocarbon group. In the compound represented by the chemical formula 1, R ¹ and R ² are independently selected hydrogen or a methyl group, and R ³ is a divalent linking group such as an aliphatic group or an aromatic group. Examples include an alkylene group and an 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.

Such a compound is disclosed in JP-A-59-80662.
JP-A-60-178882, JP-A-60-17862
Known compounds synthesized by a known synthesis method described in JP-A-18761, JP-A-63-170358, JP-A-7-53516 and the like can be used. Such compounds are available from Maruzen Petrochemicals Co.
It is commercially available as I series and ANI series.

The thermosetting imide may be used alone as it is, but when used in combination with an adhesive generally used as an adhesive such as an epoxy adhesive or a polyurethane adhesive, high heat resistance is obtained. While maintaining the above conditions, productivity, coatability of the adhesive and the like can be improved. in this case,
The thermosetting imide and another adhesive may be simultaneously dissolved in a solvent and mixed. It is also possible to add a curing agent, a thickener and a filler to the thermosetting imide in order to improve coating properties and adhesion. For example, since the curing temperature of the thermosetting imide is 200 ° C. or higher, it may be difficult to bond with a general laminating roll. In such a case, temporary bonding by a laminating roll becomes possible by using an epoxy resin that can be cured at a low temperature with a thermosetting imide or a curing agent that promotes curing.

In the present invention, as a method for preparing a support by laminating a polyimide film or a polyamide film, an adhesive solution obtained by dissolving an imide monomer in an organic solvent is applied to the bonding surface of the polyimide film or the polyamide film and dried. After evaporating off the solvent,
A general dry lamination method in which the film is bonded to the other film using a heated laminating roll can be used.However, since the curing start temperature of the thermosetting imide is high, after bonding by the laminating roll, heating for sufficiently curing is performed. There is a need to do.

FIG. 1 is a view for explaining a laminating method used for manufacturing the floppy disk of the present invention. The first heat-resistant film 1 is pulled out of a roll, and an adhesive solution 3 is continuously applied to the surface by a coater 2. Next, the heat-resistant film 1 to which the adhesive has been applied is dried under heating in a solvent drying furnace 4, and then dry-laminated on the second heat-resistant film 5 and the laminate roll 6 drawn out of the roll, and is uncured. A laminate film 7 is formed. The uncured laminate film 7 is processed in a curing furnace 8 to promote polymerization of the adhesive layer to obtain a sufficiently bonded laminate film 9, which is wound around a roll. In the above explanation,
Although the method for producing a laminated film in which two films are laminated has been described, a film produced using three or more films may be used.

As a method of applying the adhesive solution on a heat-resistant film such as a polyimide or polyamide film, a general method such as a wire bar method, a gravure method, a spray method, a knife coating method, a spin coating method, a dip coating method, or the like is used. Can be used. Adhesive application thickness is 0.1 ~
It is 10 μm, preferably 1 to 5 μm.

The solvent used for dissolving the thermosetting imide varies depending on the type of R ^{3 in} the chemical formula 1 of the thermosetting polyimide, but in many chemical structures, toluene, xylene, acetonitrile, cyclohexanone, It can be dissolved in methyl ethyl ketone, acetone, etc., and in some structures, can be dissolved in isopropyl alcohol, ethanol, methanol, etc. These mixed solvents can be used as the solvent.

The drying is carried out to volatilize the above-mentioned solvent. As a drying method, hot air drying, infrared drying and the like which are generally used can be used. At this time, if the solvent cannot be sufficiently dried and removed, bubbles may be generated after bonding. On the other hand, if the drying temperature is too high, the curing of the adhesive starts, which leads to a decrease in the adhesive strength in the dry laminating step. Therefore, there is an optimum drying temperature range depending on the structure of the thermosetting imide, the type of the adhesive to be added, and the type of the solvent, but the drying temperature is generally in the range of 60 ° C. to 150 ° C.

After the coating film is dried, the polyimide or polyamide film is bonded by pressing the polyimide or polyamide film as the bonding partner through a heated laminating roll. As the laminating roll, a metal heating roll using a liquid, steam or the like as a heat medium or a metal heating roll by induction heating can be used. The backup roll of the laminating roll may be the same as the laminating roll, but a resin roll or a metal roll having no heating source may be used. The temperature of the laminating roll is preferably set to 150 ° C to 250 ° C. Since the curing of the thermosetting imide is insufficient with the bonding by the laminating roll, it is necessary to further heat in a curing furnace for curing.

As a heating method, hot air heating, infrared heating and the like can be used. The heating temperature at this time depends on the thickness of the coating film.
° C, preferably in the range of 200 ° C to 250 ° C. When the temperature is lower than this, the progress of the polymerization reaction is insufficient. On the other hand, when the temperature is too high, the nonmagnetic support may be deformed or productivity may be reduced.

The heat-resistant film used in the present invention includes a polyamide film, a polyimide film and the like. Examples of the polyamide used for producing the polyamide film include a polyamide resin obtained by polycondensation of a lactam having three or more members, a polyamide resin obtained by polycondensation of an ω-amino acid, and a polyamide resin obtained by polycondensation of a dibasic acid and a diamine. No. In particular,
Examples of lactams having three or more rings include ε-caprolactam, enantholactam, capryllactam, lauryl lactam and the like. Examples of the ω-amino acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and the like. Examples of dibasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandionic acid, dodecadionic acid, hexadecadionic acid, eicosandioic acid, eicosadienedioic acid, 2,2 ,
Examples include 4-trimethyladipic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and xylylenedicarboxylic acid. Diamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediaminepentamethylenediamine, undecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, cyclohexanediamine, bis -(4,4'-aminocyclohexyl) methane, meta-xylylenediamine and the like. Examples of the polymer obtained by polycondensing them or the copolymers thereof include nylon 6, nylon 7, nylon 11, nylon 12, nylon 6.6, nylon 6.9, nylon 6.11, and nylon 6. 12,
Nylon 6T, Nylon 6I, Nylon MXD6, Nylon 6 / 6.6, Nylon 6/12, Nylon 6/6
T, nylon 6 / 6I, nylon 6 / MXD6 and the like.

Examples of the polyimide film include a polypyromellitic imide film and a polyetherimide film.

As the polyamide film and the polyimide film, a film having a thickness of 20 to 100 μm can be used. It is particularly preferable that this film has a roughened surface of the adhesive surface in order to enhance handling properties during production such as transport and winding, and a very smooth magnetic film surface in order to enhance electromagnetic conversion characteristics. The surface roughness of the bonding surface is preferably 1 nm to 5 nm in center line average roughness Ra, and the surface roughness of the magnetic film surface is 2 nm or less in Ra.
_max is preferably 60 nm or less.

The polyimide film or the polyamide film can be bonded by the adhesive containing the thermosetting imide of the present invention. However, if the adhesive strength is insufficient, the film bonding surface is subjected to corona treatment, glow treatment, etc. Quality can increase the adhesion.

Further, by providing minute projections having a very low height on the surface of the magnetic recording medium, 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 magnetic film surface of the substrate has a fine projection structure. This microprojection structure has the effect of significantly improving the handleability of the support after lamination. 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 a resin having sufficient heat resistance is preferable to ensure heat resistance, and such a material is used as an adhesive in the present invention. It is particularly preferable to use a thermosetting imide or a thermosetting silicone resin. The height of the microprojections is 5 to 60 nm, preferably 10 to 30 nm,
The density is 0.1 to 100 / m ² , preferably 1 to
10 / 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. 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.

On the other hand, when the surface properties of the magnetic film surface of a heat-resistant film such as a polyimide film or a polyamide film are not as smooth as the above-mentioned films, it is necessary to first form an undercoat film on the magnetic film surface of the film for the purpose of smoothing. There is.
In this case, the material of the undercoat film has a high smoothing effect,
It is preferable to use a thermosetting imide or a thermosetting silicone resin. The thickness of this undercoat film is 0.1 to 3 μm
Is preferred. The thermosetting resin can be prepared, for example, by a method of applying a monomer containing a silane coupling agent having an epoxy group, followed by thermosetting.

In order to enhance the uniformity of the front and back surfaces of the heat-resistant film after lamination, it is preferable to use two films and bond the respective magnetic surfaces and the bonding surfaces opposite to each other. It is also possible to laminate and use the above film. For example, when laminating three films, a thin polyamide film with a very smooth magnetic film surface is bonded to the front and back of an inexpensive thick polyimide film with very little warpage, or when laminating four films After laminating two relatively thick and inexpensive polyimide films to reduce warpage, it is possible to laminate very smooth thin polyamide films on the front and back surfaces.

The ferromagnetic metal thin film serving as a magnetic layer in the magnetic recording medium of the present invention is formed by sputtering. Examples of the composition of the magnetic layer include metals or alloys mainly composed of cobalt. Specifically, Co-Cr, Co-N
i-Cr, Co-Cr-Ta, Co-Cr-Pt, Co
-Cr-Ta-Pt, Co-Cr-Pt-Si, Co-
Cr-Pt-B or the like can be used. In particular, Co-Cr-Pt, Co-Cr-Pt-T are used to improve electromagnetic conversion characteristics.
a is preferred.

The thickness of the magnetic layer is desirably 10 to 30 nm. In this case, it is preferable to provide a base film for improving the magnetostatic properties of the magnetic film. The base film may be composed of a metal or an alloy. Specifically, Cr, V, Ti, Ta, W , Si or the like or an alloy thereof can be used, and among them, Cr and Cr-Ti are particularly preferable. The thickness of the underlayer is 5 nm to 50 nm, preferably 10 nm to 30 nm. Further, in order to 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, Hf, Nb, Mn, Ni,
Al, Ru, Ti or an alloy thereof, particularly preferably Ta, Cr, Ti or an alloy thereof, preferably has a thickness of 15 to 60 nm. When a magnetic film is formed by a sputtering method, it is preferable to form a film while the substrate is heated, and it is preferable to use DC magnetron sputtering and set the substrate temperature to about 200 ° C.

In the magnetic recording medium of the present invention, a protective film is preferably provided on the ferromagnetic metal thin film, and the running durability and the corrosion resistance can be remarkably improved by the protective film. Silica, alumina, titania,
Oxides such as zirconia, cobalt oxide and nickel oxide, nitrides such as titanium nitride, silicon nitride and boron nitride, silicon carbide, chromium carbide and carbides such as boron carbide;
Examples of the protective film include carbon such as graphite and amorphous carbon. As the protective film, a hard film having a hardness equal to or higher than that of the head material is preferable. Further, a film that hardly causes seizure during sliding and has a stable and stable effect is most preferable. One example is a hard carbon film called diamond-like carbon.

The diamond-like carbon film is an amorphous carbon film formed by a plasma CVD method, a sputtering method, or the like, and is microscopically a mixture of clusters formed by sp ² bonds and clusters formed by sp ³ bonds. The hardness of this film is Vickers hardness of 1000 kg / mm ² or more, preferably 2000 kg / mm ² or more. When measured by Raman spectroscopy of the diamond-like carbon film, it is confirmed that a main peak called a so-called G peak is detected around 1540 ^-1 cm and a shoulder called a so-called D peak is detected at 1390 cm ^-1. Can be. These diamond-like carbon films can be prepared by a sputtering method or a CVD method. However, the CVD method is used in that the productivity, the stability of quality, and the good abrasion resistance can be secured even with an ultrathin film having a thickness of 10 nm or less. It is preferable to produce, particularly, a chemical species generated by decomposing a carbon-containing compound such as alkane such as methane, ethane, propane, and butane, or alkene such as ethylene and propylene, or alkyne such as acetylene by a plasma. It is preferable to apply a negative bias voltage to the substrate and accelerate the deposition. When the thickness of the hard carbon protective film is large, the electromagnetic conversion characteristics are deteriorated and the adhesion to the magnetic layer is reduced, and when the thickness is small, the abrasion resistance is insufficient. Preferably it is 5 to 20 nm.

In the magnetic recording medium of the present invention, in order to improve running durability and corrosion resistance, it is preferable to provide a lubricant or a rust inhibitor on the magnetic film or the protective film. 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 part or all of the alkyl groups of the hydrocarbon-based lubricant are substituted with fluoroalkyl groups or perfluoropolyether groups. 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.

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

The above lubricants are used alone or in combination of two or more. As a method of applying these lubricants on a magnetic film or a protective film, a lubricant is dissolved in an organic solvent and applied by a wire bar method, a gravure method, a spin coating method, a dip coating method, or a vacuum evaporation method. What is necessary is just to make it adhere. The amount of the lubricant to be applied is 1 to 30 mg / m ^2.
Preferably, 2 to 20 mg / m ² is particularly preferred.

Examples of the rust preventives usable in the present invention include nitrogen-containing heterocycles such as benzotriazole, benzimidazole, purine and pyrimidine, derivatives having an alkyl side chain introduced into the mother nucleus thereof, benzothiazole, 2-mercapto And nitrogen- and sulfur-containing heterocycles such as benzothiazole, tetrazaindene ring compounds and thiouracil compounds, and derivatives thereof. The tetrazaindene ring compounds that can be used for such purposes include the following.

[0042]

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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.

[0044]

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Here, R is selected from the same groups as those described above for the tetrazaindene ring compound.

[0046]

The present invention will be described below with reference to examples.

Example 1 A spherical silica particle having a particle diameter of 25 nm and a thermosetting imide resin (BA manufactured by Maruzen Petrochemical Co., Ltd.) were formed on a magnetic film surface of a polyamide film having a maximum protrusion roughness of 60 nm and a thickness of 25 μm on the magnetic film surface.
NI-NB) was dissolved in cyclohexanone, filtered through a filter having a pore size of 0.2 μm, and then applied.
Drying was performed with hot air at 20 ° C. for 30 seconds to form microprojections having an average height of the projections of about 20 nm and a projection density of 5 / μm ² . Further, a solution of a mixture of a thermosetting imide and an epoxy resin serving as an adhesive in methyl ethyl ketone (BANI-100 manufactured by Maruzen Petrochemical Co., Ltd.) having a pore diameter of 0.2
After filtration through a filter of μm, the mixture was applied by a gravure coating method, and dried with hot air at 80 ° C. for 30 seconds to form an adhesive layer having a thickness of 1 μm. An adhesive surface of the polyamide film, to which no adhesive was applied, was adhered to the polyamide film via a laminating roll heated at 150 ° C., thereby producing a support.

Next, the support was cut out, fixed by being inserted between circular holders to which a uniform tension was applied, and the support was heated at 250 ° C. for 3 hours to cure the adhesive. This support was placed in a sputtering apparatus for forming a magnetic film while being sandwiched between holders, and after the support was heated to 200 ° C., a 30 nm Cr—Ti underlayer was formed by DC magnetron sputtering, and then Co -Cr-Pt
A 30 nm magnetic film was formed. The base film and the magnetic film 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 film by a plasma CVD method using methane as a raw material. Next, the sample was taken out of the holder, a sample for checking adhesion was cut out, and a perfluoropolyether-based lubricant (FOMBLIN Z-DO manufactured by Ausimont Co., Ltd.) was placed on the protective film of the remaining sample.
L) with a fluorinated solvent (FC-77 manufactured by Sumitomo 3M Limited)
The solution dissolved in the above was filtered through a filter having a pore diameter of 0.2 μm, and then applied by a dip coating method to prepare a lubricating film having a thickness of 1 nm. This sample was punched into a 3.5-inch magnetic disk to produce a floppy disk.

Example 2 A polyimide film having a maximum protrusion roughness of 0.2 μm and a thickness of 50 μm was coated on a thermosetting imide (BANI manufactured by Maruzen Petrochemical Co., Ltd.).
-NB) was dissolved in a mixed solvent of toluene and cyclohexanone, and the solution was filtered through a filter having a pore size of 0.2 µm.
After being applied by a dip coating method, it was dried at 250 ° C. for 3 hours to prepare an undercoat film (smoothing layer) having a thickness of 1 μm. Further, spherical silica particles having a particle diameter of 18 nm and thermosetting silicone 3-glycidoxypropyltrimethoxysilane 20.0% by weight phenyltriethoxysilane 20.0% by weight ethanol 44.6% by weight cyclohexanone 0 on this undercoat film 6.6% by weight Purified water 10.0% by weight Hydrochloric acid (1 mol / l) 4.4% by weight A mixture consisting of 0.4% by weight of aluminum acetylacetonate was filtered through a filter having a pore size of 0.2 μm, and then dipped. The coating was applied by a coating method and dried at 250 ° C. for 1 hour to form minute projections on the surface of the undercoat film. The surface roughness of this undercoat film is 50 nm in maximum projection roughness, the average height of the fine projections is 15 nm, and the projection density is 10 protrusions / μm.
^{Was 2} . Next, a methyl ethyl ketone solution of a thermosetting imide (BANI-X manufactured by Maruzen Petrochemical Co., Ltd.) was filtered through a filter having a pore diameter of 0.2 μm on one side of the sample, applied by a spray method, and dried at 80 ° C. for 1 minute. Then, an adhesive layer having a thickness of 2 μm was prepared. Similarly to this sample, a 50 μm-thick polyimide film having surface protrusions was bonded to a smooth glass plate so that the front and back surfaces were symmetrical. This sample was heated at 250 ° C. for 3 hours to cure the thermosetting imide, thereby producing a support. Using this support, a magnetic film, a protective film, and a lubricating film were formed in the same manner as in Example 1 to produce a floppy disk.

Comparative Example 1 A floppy disk was prepared in exactly the same manner as in Example 1 except that the adhesive used for lamination in Example 1 was changed to a solution of a single methyl ethyl ketone of epoxy resin (Epicoat 828).

Comparative Example 2 The adhesive used in laminating in Example 1 was changed to an N, N-dimethylacetamide solution of a thermosetting polyimide resin (CT4112 manufactured by Toshiba Chemical Co.) alone, and the drying temperature was set to 120 ° C. A floppy disk was produced in the same manner as in Example 1, except for the change. However, since the thermosetting polyimide resin solution had a high viscosity and could not be filtered, the filtration step was omitted.

Comparative Example 3 The support had a maximum protrusion roughness of 0.1 μm on both sides and a thickness of 5
A sample was prepared in exactly the same manner as in Example 1 except that a 0 μm polyamide film was used without being laminated.

Comparative Example 4 The support had a maximum projection roughness of 0.2 μm on both sides and a thickness of 1
A sample was prepared in exactly the same manner as in Example 2 except that a 00 μm polyimide film was used without being laminated.

The prepared samples were evaluated by the following evaluation methods. (Evaluation Method) (1) Appearance The completed medium surface was visually observed and observed with an optical microscope (100 times), and the presence or absence of foreign matter caused by the support and the occurrence of bubbles were examined. (2) Adhesiveness A sample was cut into a square of 5 mm square without applying a lubricant, and a polyethylene adhesive tape (Nitto # 31B) was attached to both sides of the sample, and the adhesive tape was supported when the adhesive tape was peeled off. The presence or absence of peeling at the body laminate interface was examined. (3) Curl value A floppy disk punched out to 3.5 inches was set upright, and rotated at 60 rpm while the center of the disk was chucked by a ring. Then, a laser displacement meter scans a range of a radial position 20 mm to 45 mm from the inner circumference with respect to this fixed radial direction, and a difference between a position where the disk-displacement meter distance is shortest and a position where the distance is longest is determined as a curl value. .

Based on the above evaluation method, the samples prepared in each of Examples and Comparative Examples were evaluated, and the evaluation results are shown in Table 1.

[0056]

Table 1 Sample Support Laminate Adhesive Appearance Adhesive Curl Amount (mm) Example 1 Thermosetting imide of 25 μm Good Good 0.2 Polyamide 2 layer epoxy resin Example 2 Thermosetting imide of 50 μm Good Good 0. 1 Polyimid 2 layer Comparative example 1 Epoxy resin of 25 μm good and poor 1.1 Polyamid 2 layer Comparative example 2 25 μm thermosetting polyimid foam Small amount of air bubbles Good 0.5 Polyamit 2 layer Foreign matter intrusion Comparative example 3 50 μm None Good − 2.0 or more Polyamid 1 layer (measurable) Comparative Example 4 None of 100 μm Good-0.9 Polyimid 1 layer

As can be seen from the above Examples, it can be seen that Examples 1 and 2 prepared according to the present invention are all excellent in appearance, adhesiveness and curl amount. On the other hand, in Comparative Example 1 in which an epoxy resin was used as the laminating adhesive, the adhesive strength was lowered by keeping the laminate at a high temperature.
Further, in Comparative Example 2 using a thermosetting polyimide resin, bubbles were slightly generated due to the residual solvent, and deformation of the medium due to foreign matters caught in the bonding surface was observed in some places. In Comparative Examples 3 and 4 in which one film was used as a support without laminating, the original warpage of the film remained and the curl amount increased.

[0058]

According to the production method of the present invention, the adhesiveness of the heat-resistant film used as the support is improved, and as a result, the amount of curl is reduced, and a floppy disk having excellent dimensional stability and electromagnetic conversion characteristics is obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a laminating method used for manufacturing a floppy disk of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... First heat resistant film, 2 ... Coater, 3 ... Adhesive solution, 4 ... Solvent drying furnace, 5 ... Second heat resistant film, 6
... Laminate roll, 7 ... Uncured laminate film, 8 ... Curing oven, 9 ... Laminated film

Claims (2)

[Claims] 1. A method for producing a floppy disk medium having a magnetic film on at least one surface of a non-magnetic support on which at least two heat-resistant films are laminated, wherein a heat-curable imide-containing adhesive is provided on the heat-resistant film surface. A method for producing a floppy disk, comprising: forming a magnetic layer on a support laminated by dry lamination after forming an agent layer; and forming a magnetic layer on the support. 2. The heat-resistant film is a polyamide film,
2. The method for manufacturing a floppy disk according to claim 1, wherein the method is selected from polyimide films.