JPH05135360A - Manufacture of magnetic disk - Google Patents

Abstract

PURPOSE:To enable a mass production of a recording disk superior in recording/ reproducing characteristics, in the manufacturing method of the recording disk. CONSTITUTION:When a disk-like recording sheet 2 consisting of a flexible supporting body 4 and a recording layer 3 which is provided on one surface and tapered parts of an annular projection 6 at an inner peripheral side of a disk-like base 1 and an annular projection 7 at an outer peripheral side, are stuck by pressurizing by using a press member 30, an adhesive material 20 is provided between the disk-like recording sheet 2 and the disk like base 1 and the adhesion is accelerated by heating the adhesive material 20 by ultrasonic waves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing a recording disk in which a recording sheet is adhered to at least one surface of a disk-shaped substrate having a recess on its surface so that the recess becomes a void. In particular, the present invention relates to a manufacturing method of a recording disk excellent in mass production suitability.

[0002]

2. Description of the Related Art In recent years, there have been increasing demands for higher density and higher capacity of recording disks used for recording information in computers and the like.

As a typical recording disk, a flexible sheet having a recording layer provided on a flexible support is punched into a disk shape and inserted into a jacket. A rigid disc having a recording layer formed on a base is known.

Since the floppy disk uses a flexible support, it has excellent running durability especially against sliding with the head, and the center line average roughness of the recording surface due to the surface treatment of the recording layer. Since Ra can be made extremely low, high density recording is possible. However, if the track density is increased in order to increase the recording capacity, there is a problem that the head is apt to cause track deviation due to thermal contraction of the support.

On the other hand, in the rigid disc, the recording layer is formed on the rigid base having less flexibility, so that the track deviation of the head due to heat shrinkage or the like is less likely to occur. That problem has been solved.

In the manufacture of rigid discs,
The surface of a substrate such as aluminum is polished to improve its surface property so that high density recording can be performed, and then a recording layer is formed on it. However, it is difficult to set the center line average roughness Ra of the substrate surface to 0.01 μm or less, and there is a limit to high density recording.

In addition, since the rigid disk has no flexibility in the base, the recording layer cannot be continuously formed, and the recording layer is destroyed by a large impact force when the head and the recording layer come into contact with each other. There was a problem in use of.

In view of the problems of these floppy disks and rigid disks, in recent years, a flexible disk sheet having a recording layer provided on one surface of a flexible support has a rigid disk-shaped substrate provided with wide annular recesses on both surfaces. There is proposed a recording disk in which the above-mentioned concave portion is attached so as to form a void.

Since this type of recording disk has a rigid base like a rigid disk, it is less likely that track displacement of the head will occur due to heat shrinkage or the like, but unlike a rigid disk, the recording surface is flexible. Therefore, even if the head comes into contact with the recording surface, or even if high-density recording / reproduction is performed while the head is in sliding contact with the recording surface, the recording layer is less likely to be destroyed. Also,
Since the above-mentioned advantages of the floppy disk can be used as they are, the surface property is good and the running durability is excellent. That is, it can be said that this type of recording disk has the advantages of both a floppy disk and a rigid disk.

The manufacturing method is described in, for example, US Pat.
It is described in No. 3,097.

This manufacturing method comprises adhering a flexible disc-shaped recording sheet 2 as shown in FIG. 7 to the disc-shaped substrate 1 as shown in FIG. 8 in section.

As shown in FIG. 7, the disc-shaped recording sheet 2 has a recording layer 3 provided on a flexible support 4.
After being bonded to the disc-shaped substrate 1, an extra portion is cut out in accordance with the shape of the disc-shaped substrate 1.

The disc-shaped base 1 is constructed so that a gap 5 is formed between the disc-shaped recording sheet 2 and the disc-shaped recording sheet 2 when the disc-shaped recording sheet 2 is adhered thereto. That is, as shown in FIG. 8, the disk-shaped base 1 has an inner peripheral side annular convex portion 6 having a taper surface gradually decreasing toward the inner side and an outer peripheral side annular convex portion 7 having a taper surface gradually decreasing toward the outer side. And an annular recess 8 is formed between them. Further, a hole 9 having a predetermined diameter is formed in the central portion of the disk-shaped base 1.

As shown in FIG. 9 by enlarging the cross section of the outer peripheral portion, the recording layer 3 of the disc-shaped recording sheet 2 is on the front side, and the flexible support 4 thereof is an annular protrusion on the inner peripheral side of the disc-shaped base 1. The recording disk 10 is formed by adhering the taper surface of the portion 6 and the taper surface of the outer peripheral annular projection 7 with an adhesive. At this time, the disc-shaped recording sheet 2 is radially stretched so as not to sag on the disc-shaped substrate 1.

A gap 5 between the disc-shaped base 1 and the disc-shaped recording sheet 2 is formed at a position corresponding to the annular recess 8 of the disc-shaped base 1. When the recording disk 10 is used, even if the head contacts the recording layer 3, the gap 5 serves as a cushion,
The destruction of the recording layer 3 by the head is prevented. As a result, the recording layer and the head are more easily brought into close contact with each other, and sliding suitable for high-density recording becomes possible.

In the method of manufacturing such a recording disc, the most important step, which requires accuracy, is the step of adhering the recording sheet to the disk-shaped substrate. That is, it is necessary to apply a uniform and constant tension to the recording sheet adhered on the disk-shaped substrate, and for that purpose, it is necessary to apply an appropriate tension to the recording sheet in the adhering step. If it takes a long time to complete, due to the creep phenomenon of the flexible support, etc., the recording sheet will have local slack, wrinkles, or other uneven tension, and the characteristics of the recording medium will deteriorate. Sometimes.

Various types of adhesives and bonding methods have been proposed in this bonding step. For example, JP-A-58-189838 proposes a method of using a thermosetting adhesive and curing the adhesive by applying heat with an infrared lamp or an oven.
Further, in Example 1, it is described that after applying the room temperature curing type epoxy adhesive, the disk-shaped substrate is pressed against the recording sheet in the stretched state to cure it.

However, when a thermosetting adhesive is used, it takes a long time to cure, and thus the mass productivity of recording disks becomes low. Moreover, since the stretched recording sheet is left in a high temperature environment, it causes creeping of the flexible support (polyethylene terephthalate, etc.) of the recording sheet, which causes the interface between the recording layer and the head to deteriorate. May be. In addition, since dust and the like adhering to the recording layer may be fixed in a high temperature environment and become a defective portion at the time of data recording / reproduction, a highly clean atmosphere is required and expensive equipment is required. Become.

Even when the room temperature-curable epoxy adhesive is used, it takes a very long time to cure, so that the mass productivity of the recording disk becomes low.

Japanese Unexamined Patent Publication (Kokai) No. 62-80828 discloses an example in which a solvent-free adhesive is used to press the edges at 200 ° C. for 0.5 second. However, no specific method is disclosed, and in order not to cause defects such as slack and wrinkles of the recording sheet due to the adverse effect of heating even on the recording sheet around the adhesive portion, high temperature pressurization is performed. It was difficult to limit the effect to only the adhesive portion.

Further, a method of terminating the bonding process within a short time by irradiation with radiation is disclosed in JP-A-61-151838 and JP-A-62-80829. Therefore, a large-scale facility was required, which was a problem in terms of operability and production cost.

Japanese Patent Laid-Open No. 59-90235 and US Pat. No. 4,
No. 670,072 has a description of directly ultrasonically welding a disc-shaped substrate and a recording sheet. However, the combination of materials that can be welded in this way is extremely limited, and recording of generally used inexpensive and good performance polyethylene terephthalate (PET), polyimide (PI) having extremely high heat resistance, etc. Even if the sheet material and the disc-shaped base material such as polyetherimide (PEI) having a good rigidity and expansion coefficient are directly ultrasonically welded, it is almost impossible to bond them.

Further, JP-A-59-90235 describes that it is difficult to bond polyethylene terephthalate with an adhesive, but in recent years, an adhesive suitable for bonding polyethylene terephthalate has been considerably known. As a result, the bonding using an adhesive is not difficult, and it is no longer necessary to directly ultrasonically weld the disk-shaped base and the recording sheet.

As described above, in the bonding step in manufacturing a recording disk, it has been desired to reliably bond the recording sheet to the disk-shaped substrate within a short time at an appropriate production cost. There has been no known method for satisfying the requirement.

[0025]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention aims to manufacture a recording disk having a gap between a recording sheet and a disk-shaped substrate in a state of excellent recording and reproducing characteristics. It is an object of the present invention to provide a manufacturing method which is excellent in mass production suitability.

[0026]

According to the method of manufacturing a recording disk of the present invention, when the radially extending disk-shaped recording sheet is adhered to a disk-shaped substrate while applying pressure using a pressure member, the disk-shaped recording sheet is used. An adhesive is provided between the disk-shaped substrate and the disk-shaped substrate, and the adhesive is accelerated by ultrasonically heating the adhesive.

In the present invention, the adhesive is usually sandwiched between a disk-shaped substrate as an adherend and a disk-shaped recording sheet in a stretched state, and ultrasonic vibration is applied from the outside while applying pressure with a tool horn to bond the bonded portion. Adhesion is completed by melting and curing the adhesive using the mechanical friction and viscoelastic behavior of.

As the adhesive, a liquid adhesive may be applied to at least one of the disc-shaped recording sheet and the disc-shaped substrate and dried before ultrasonic heating, or in the form of film, pellets, A string-shaped or B-stage-shaped material may be placed between the disk-shaped recording sheet and the disk-shaped substrate and ultrasonically heated while applying pressure. Using double-sided adhesive tape as an adhesive simplifies the process,
Further, there is an advantage that there is no problem regarding equipment and safety associated with the use of the solvent.

A typical recording disk manufactured by the present invention is a magnetic disk having a magnetic layer as a recording layer. However, the present invention is not limited to the magnetic disk, and a phase change type optical recording medium, an optical disk. It can be used for manufacturing various recording disks such as magnetic recording media.

As the disc-shaped substrate, metals such as aluminum and aluminum alloy, glass, synthetic resin, resin containing filler, and combinations thereof can be used.

Since a disc-shaped substrate made of synthetic resin can be manufactured in large quantities by injection molding, it is generally inexpensive.

Further, a crystalline polymer having heat resistance and an amorphous polymer having a glass transition temperature of 80 ° C. or higher are preferable materials because they are not deformed by storage at a high temperature.

Specifically, polycarbonate, polyether imide, polyphenyl sulfide, polyimide,
Polysulfone, polyacrylate, polyether sulfone, polyether ether ketone, etc. are preferred materials.

In order to reduce the expansion coefficient of the disk-shaped substrate, metal oxides such as TiO ₂ and SiO ₂ and BaS are used.
O _4, may be mixed with glass fibers or the like 5-50 wt%.

The disc-shaped recording sheet is formed of a material suitable for the intended use of the recording disc. For example, when the recording disk is a magnetic disk, the material used for a so-called floppy disk can be used.

In this case, a plastic film such as polyethylene terephthalate is generally used as the flexible support of the disk-shaped recording sheet, and a biaxially oriented polyethylene terephthalate film (PET) is particularly preferable.
Further, Ra (center roughness) of the surface on which the recording layer (magnetic layer) is provided is preferably 0.01 μm or less in order to increase the recording density of the magnetic disk.

When the recording layer is, for example, a magnetic layer, magnetic iron oxide or a ferromagnetic alloy powder is coated with a binder or the like, or a vapor deposition method such as vacuum deposition, sputtering or ion plating, a plating method or the like. Can be formed by using.

If the flexible support of the disk-shaped substrate or disk-shaped recording sheet is made of a hard thermoplastic or is compatible with each other, it is welded by ultrasonic heating without an adhesive. It is possible to do so. However, even in such a case, it is preferable to adhere via an adhesive as in the present invention in order to ensure reliable adhesion. Further, the flexible support of the disk-shaped substrate or disk-shaped recording sheet to be adhered is polyethylene terephthalate (PET), polyimide (PI), polyetherimide (PEI), polyethylene naphthalate (PEN),
When it is made of polyphenylene sulfide (PPS), aramid, polyolefin (PO), polyacetal (POM), thermosetting plastic, etc., welding is difficult and it is necessary to use an adhesive.

A typical adhesive used in the present invention is a hot melt adhesive, but an acrylic adhesive, a thermosetting epoxy resin, or the like can also be used.

As the base polymer of the hot melt adhesive, a rubber such as copolyester, polystyrene butadiene copolymer, acrylonitrile butadiene copolymer, polystyrene isoprene copolymer, ethylene butylene copolymer, polyisobutylene, polybutadiene, butyl rubber, etc. One or more resins selected from the group consisting of resins, polyolefin-based copolymers such as polyethylene, polypropylene, ethylene vinyl acetate copolymer and butyl acrylate vinyl acetate copolymer can be used.

Examples of the tackifier to be added to these base polymers include natural resins such as rosin, hydrogenated rosin and rosin ester and their modified products, aliphatic, alicyclic, aromatic, petroleum resins and terpene resins, terpenes. , Phenol resin, coumarone resin and the like, and as the softening agent, process oil, paraffin oil, castor oil, polybutene, polyisoprene and the like are used.

If desired, the hot melt adhesive may be blended with additives such as a filler, an antiaging agent, an ultraviolet protective agent, etc. to improve heat resistance, weather resistance and the like.

The blending ratio of these is 100 to 600 parts by weight of tackifier and 0 part of softening agent, based on 100 parts by weight of the base polymer.
The softening point is preferably 140 ° C or lower, more preferably 120 ° C or lower, and the melt viscosity at 140 ° C is 1000 poise or lower, more preferably 160 ° C.
Blend so that it becomes 1000 poise or less.

The thickness of the adhesive layer is generally 1 to 100 μm, preferably 3 to 20 μm.

In order to enhance the adhesive effect, a groove or a hole may be provided in the bonded portion of the disk-shaped substrate, and the adhesive may be placed in the groove or hole. Further, one or both of the adhesive surfaces may be subjected to a physical surface treatment such as corona discharge, glow discharge, flame treatment or the like in order to facilitate the adhesion.

When the disk-shaped substrate is made of metal, the metal has a very high thermal conductivity as compared with other materials, so that the heat generated at the bonded portion due to ultrasonic energy is likely to escape, and the adhesive is sufficiently melted. Acceleration of curing may not be achieved in a short time. There are various methods to prevent this, but as an example,
Prior to the supply of the adhesive, it is possible to treat the bonded portion with a primer for the purpose of preventing diffusion due to conduction of heat generation. For example, an aluminum disc-shaped substrate is coated with NBR-phenolic primer at a thickness of 0.1 to 0.15 mm.
It can be adhered using a phenoxy resin adhesive after being applied so that Also, when a polyurethane rubber-based adhesive is used, the adhesion is improved by using various primers.

When the flexible support of the disk-shaped recording sheet is made of thermosetting plastic, it is effective to use a thermosetting or composite thermosetting adhesive.
However, a liquid substance wets the interface, but may not be cured in a short time and may stick out from the coated surface. Therefore, it is desirable that the liquid substance is at least in the B-stage or solid state and can be cured within a few seconds at the latest.

The adhesive is selected according to the material of the adherend, but when a chloroprene / phenolic adhesive, polyurethane rubber adhesive, NBR-thermoplastic resin adhesive, polyamide adhesive or the like is used, it is generally 1-2. Good adhesion is obtained in seconds.

As the pressing member, it is preferable to use a member having a shape that presses only the adhesive portion of the disk-shaped recording sheet and its vicinity and does not affect the recording surface.

After the disc-shaped base and the disc-shaped recording sheet are adhered to each other, heat treatment may be performed to remove the anisotropy of the flexible support of the disc-shaped recording sheet. The temperature of this heat treatment is preferably above the glass transition point of the flexible support.
The temperature is 120 ° C or less, and the time may be set between 24 hours and 3 seconds depending on the temperature. After the heat treatment, it is cooled to room temperature.

[0051]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a recording disk and a pressing member in an adhering step of a method of manufacturing a recording disk according to an embodiment of the present invention.

Recording disc manufactured in each of the following examples
Since 10 has substantially the same structure as that shown in FIGS. 7 to 9, each member thereof is denoted by the same reference numeral as that shown in FIGS.

The embodiment shown in FIG. 1 is for producing a single-sided recording disk in which a disk-shaped recording sheet 2 is provided on only one surface of a disk-shaped substrate 1. In this embodiment, the pressing member 30 is a tool horn having an annular convex portion, and the disc-shaped recording sheet 2 in a radially stretched state on the upper surface of the disc-shaped base 1 is projected on the inner peripheral annular shape. The taper surface of the portion 6 and the taper surface of the outer peripheral side annular convex portion 7 are adhered while being pressed by the annular convex portion of the pressing member 30 via the adhesive 20. At this time, ultrasonic waves are applied to the pressing member 30 from the ultrasonic vibrator through the fixed horn. A metal pedestal 50 having a Teflon coating 40 with a thickness of 0.5 mm is arranged on the lower surface of the disk-shaped base 1 to fix the disk-shaped base 1 at a predetermined position. The ultrasonic vibration of the pressure member 30 accelerates the adhesive action by hardening the adhesive 20 when it is thermosetting and plasticizing it when it is thermoplastic. Pressure member 30
Has a structure in which the disc-shaped recording sheet 2 on the gap 5 is not touched, so that only the vicinity of the bonded portion is heated, and the adverse effect of heating does not reach the entire recording surface.

The embodiment shown in FIGS. 2 and 3 is to manufacture a double-sided recording type recording disk in which the disk-shaped recording sheet 2A, 2B is provided on both surfaces of the disk-shaped substrate 1. In this embodiment, first, as shown in FIG. 2, similarly to the embodiment shown in FIG. 1, a disc-shaped recording sheet 2A is adhered to the upper surface of the disc-shaped base 1 with the lower surface fixed by a pedestal 50A. To do. Next, the surface to which the disc-shaped recording sheet 2A is adhered is set to the lower side, the recording surface is fixed by the pedestal 50B so as not to touch the recording surface, and the disc-shaped recording sheet 2B is adhered to the opposite surface by the same procedure. By such a two-step bonding process, strong bonding is achieved on both surfaces.

The embodiment shown in FIG. 4 is also for producing a double-sided recording type recording disk in which the disk-shaped recording sheets 2A and 2B are provided on both surfaces of the disk-shaped substrate 1. Here, the pressing member 30 and the pedestal 50 'are used to simultaneously bond the disk-shaped recording sheets 2A and 2B to both surfaces of the disk-shaped substrate 1 with the adhesive 20. By optimizing the materials and dimensions of the support for the disc-shaped recording sheet, the disc-shaped substrate, and the adhesive, and the structure and conditions of the ultrasonic heating means, it is possible to efficiently perform the double-sided bonding on both sides in this one-step bonding process. Adhesion can also be achieved.

FIG. 5 is an enlarged sectional view showing a part of the outer peripheral portions of the recording disk and the pressing member at the time of bonding.
This drawing shows an example in which a hot melt adhesive 20 is applied circumferentially on the adhesive surface of the disk-shaped substrate 1 using a dispenser (not shown).

FIG. 6 is an enlarged sectional view similar to FIG. 5 in another embodiment. Here, the same members as those in the embodiment shown in FIG. 5 are designated by the same reference numerals. In the embodiment shown in FIG. 6, the adhesive 20 'has adhesive layers 24 on both sides of the support 22.
Is a concentric double-sided adhesive film provided with.

Note that, in these figures, a jig for applying tension for radially stretching the disk-shaped recording sheet is not particularly shown.

Example 1 Production of Disc Recording Sheet A biaxially stretched and oriented polyethylene terephthalate film having a thickness of 32 μm and a width of 120 mm was used as a flexible support, and a magnetic coating solution having the following composition was provided on one side thereof. The final recording layer (magnetic layer) was coated so that the thickness was 2 μm, dried, and the recording layer was surface-treated with a calendar to obtain a recording sheet (magnetic sheet). (Magnetic coating liquid) γ-Fe ₂ O ₃ 300 parts by weight PVC-Ac (vinyl chloride-vinyl acetate copolymer, manufactured by VYHH UCC) 40 parts by weight Epoxy resin (Epicoat 1001 manufactured by Shell Chemical Co., Ltd.) 40 parts by weight Polyamide ( Versamide 115 GM) 20 parts by weight Methyl isobutyl ketone / xylol (2/1) 800 parts by weight Manufacturing of disk-shaped substrate 40 parts of glass fiber and inorganic filler in polyetherimide
A rigid disc-shaped substrate containing 100% was manufactured by injection molding.

The shape of the disk-shaped base is as shown in FIG. 8, and the outer diameter r ₁ and the inner diameter r ₂ of the disk-shaped base 1 are respectively
90mm and 20 mm, the length l ₂ of the length l ₁ and the outer annular projection 7 of the inner-circumferential annular portion 6 were both 1 mm. Also,
The thickness d of the disk-shaped base 1 is 2 mm, and the depth t of the annular recess 8 is 0.
It was 2 mm.

MEK / Kemit solution K-1089 (manufactured by Toray Industries, Inc.) was attached to the adhesive surfaces of the taper portions of the inner ring-shaped convex portions 6 and the outer ring-shaped convex portions 7 of the disk-shaped substrate 1 thus obtained. A solution of toluene = 1/4 mixed solvent is used as an adhesive.
As shown in (1), it was circumferentially applied with a dispenser to a thickness of 100 μm and dried.

[0063] Then, (not shown in particular equipment therefor) annular member in a state in which the disk-like recording sheet 2A was stretched radially with having an inner diameter larger than the outer diameter r ₁ of the disc-shaped base 1 The inner peripheral annular convex portion 6 and the outer peripheral annular convex portion 7 were brought into contact with the respective tapered portions.

Further, as shown in FIG. 2, the disk-shaped base 1
Using the pressing member 30 having the annular convex portion on the surface corresponding to the adhesive of the circular recording sheet on the taper portion of each of the inner peripheral annular convex portion 6 and the outer peripheral annular convex portion 7, the outer peripheral end portion of the disc recording sheet 2A is used. And the inner peripheral edge was pressed. The width of the annular convex portion of the pressure member 30 was made slightly larger than the width of the adhesive surface. On the other hand, the back surface of the disk-shaped substrate 1 was fixed with a metal pedestal 50A having a Teflon coating 40. At the same time as pressing, ultrasonic vibration was applied to the pressure member 30 for 3 seconds to melt and cure the adhesive, thereby completing the bonding between the disk-shaped recording sheet 2A and the disk-shaped substrate 1.

Then, as shown in FIG. 3, the back side of the disc-shaped substrate 1 was turned up, and the disc-shaped recording sheet 2B was adhered to the disc-shaped substrate 1 by the same procedure.

Example 2 A double-sided adhesive type chemit film adhesive (KF-2000 manufactured by Toray Industries, Inc.) was punched in an annular shape as an adhesive instead of the chemit solution according to the size of the adhering surface. A recording disk was obtained under the same conditions as in Example 1 except that the structure shown in FIG. 6 was used.

[Comparative Example 1] An adhesive having the following composition was used. Epoxy resin (Epicoat 828 Shell Co., Ltd.) 100 parts Triethylamine 5 parts This adhesive was applied to the tapered surfaces of the inner and outer annular projections on both sides of the disk-shaped substrate so as to have a thickness of 10 μm. After that, a disc-shaped recording sheet was placed and left at 60 ° C. for 5 hours without performing ultrasonic heating.

A recording disk was obtained under the same conditions as in Example 1 except for the above.

[Comparative Example 2] An adhesive having the following composition was used. Styrene-butadiene copolymer 100 parts Methyl ethyl ketone 300 parts This adhesive is applied to the taper surfaces of the inner and outer annular projections on both sides of the disk-shaped substrate so that the dry film thickness is 10 μm, and the temperature is 100 ° C. After drying for 10 seconds, a disc-shaped recording sheet was placed and left at 60 ° C. for 5 hours without performing ultrasonic heating.

A recording disk was obtained under the same conditions as in Example 1 except for the above.

Table 1 shows the evaluation results of the samples thus obtained.

[0072]

[Table 1]

The state of adhesion was evaluated by sticking a Mylar tape on the recording sheet and peeling it at 180 °, which was repeated 50 times and observing the peeled state of the edges.

PST (Penetration Stiffness) is a force expressed by the unit of g / mm when the tip of a needle-shaped probe (spherical shape of r = 3.2 mm) is vertically pushed into a recording sheet, and is expressed in units of g / mm. The sticking condition (tension) can be easily quantified. According to the findings obtained so far, in the case of the flexible magnetic sheet, the measured value of PST and the problem of the interface between the head and the medium are correlated, and in particular, the output level becomes higher as the PST becomes higher in a certain range. , If the output exceeds a certain range, the output will saturate,
It is known that it may decrease when the upper limit is exceeded. From the results of experiments conducted by the present inventor, a desirable value of PST is 30
It has been found to be in the range of ~ 300 g / mm 2, more preferably 100-200 g / mm 2.

The output was expressed as a relative value (unit: dB) with respect to the reference disc.

The defective portion was evaluated by the number of missing pulses.

[0077]

According to the present invention, good adhesion can be completed in an extremely short time by accelerating the adhesion between the disk-shaped recording sheet and the disk-shaped substrate by using ultrasonic heating through an adhesive. Therefore, it is possible to obtain extremely high mass productivity, good quality, and yield.

In particular, as an advantage of being able to complete the bonding in a room temperature environment in an extremely short time at the time of bonding, a disc-shaped recording sheet produced by being exposed to a high temperature environment in a stretched state as in the conventional thermosetting bonding It is possible to prevent the creep and the decrease of the tension during the manufacturing process, and to prevent the warp and dimensional deviation of the substrate, and also to prevent the occurrence of defective parts due to the adhesion of adhered substances. Not only the essential problem in mass production can be solved, but also a significant improvement effect can be obtained in quality.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a recording disk and a pressing member in a bonding step of a method for manufacturing a recording disk according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a recording disk and a pressing member in a first bonding step of a method of manufacturing a recording disk according to another embodiment.

3 is a sectional view showing a recording disk and a pressing member in a second bonding step of the method for manufacturing the recording disk according to the embodiment shown in FIG.

FIG. 4 is a cross-sectional view showing a recording disk and a pressing member in an adhering step of a recording disk manufacturing method according to another embodiment.

FIG. 5 is an enlarged cross-sectional view showing an example of a bonded portion in a bonding step of a recording disk manufacturing method according to the present invention.

FIG. 6 is an enlarged cross-sectional view showing another example of the bonded portion in the bonding step of the recording disk manufacturing method according to the present invention.

FIG. 7 is a sectional view showing an example of a recording sheet used in the present invention.

FIG. 8 is a sectional view showing an example of a recording disk manufactured according to the present invention.

9 is an enlarged cross-sectional view showing a part of the outer peripheral portion of the recording disk shown in FIG.

[Explanation of symbols]

 1 Disc-shaped substrate 2 Disc-shaped recording sheet 3 Recording layer 4 Flexible support 5 Gap 6 Inner peripheral annular convex portion 7 Outer peripheral annular convex portion 8 Annular recess 9 hole 10 Recording disk 20 Adhesive 22 Support 24 Adhesive Layer 30 Pressure member 40 Teflon coating 50 Cradle

Claims (4)

[Claims] 1. A disk-shaped substrate having an inner peripheral annular convex portion having a tapered surface gradually decreasing toward the inner side and an outer peripheral annular convex portion having a taper surface gradually decreasing toward the outer side is prepared. A disk-shaped recording sheet comprising a flexible support and a recording layer provided on one surface thereof is prepared, and while the disk-shaped recording sheet is radially stretched, a flexible support for the disk-shaped recording sheet is provided. A method of manufacturing a recording disk, which comprises bonding the inner peripheral portion and the outer peripheral portion to the tapered surface of the inner peripheral annular convex portion and the tapered surface of the outer peripheral annular convex portion of the disc-shaped substrate while applying pressure using a pressing member. 2. A method for manufacturing a recording disc, comprising: arranging an adhesive between the disc-shaped recording sheet and the disc-shaped base, and accelerating the adhesive action by ultrasonically heating the adhesive. 2. The method of manufacturing a recording disk according to claim 1, wherein the adhesive is a double-sided adhesive film. 3. The disk-shaped substrate is made of metal, and the adhesive portion of the disk-shaped substrate to the disk-shaped recording sheet is primed, and then the adhesive is placed on the bonded portion. Item 3. A method of manufacturing a recording disk according to item 1 or 2. 4. The method of manufacturing a recording disk according to claim 1, wherein the recording disk is a magnetic disk.