JPH04209315A - Production of recording disk - Google Patents

Abstract

PURPOSE:To massproduce recording disks excellent in recording and reproducing characteristics by incorporating a material which can be heated by induction heating into at least one of substrate, recording sheet, pressing member, and adhesive in order to promote adhesion. CONSTITUTION:An adhesive 20 is applied on tapered surfaces of annular projections in the inner and outer circumferential areas of a substrate 1. With using two annular members having inner diameter R larger than the outer diameter (r) of the substrate 1, a disk type recording sheet 2 is brought into contact with the tapered surfaces of the annular projections 6, 7 in the inner and outer circumferential areas while the sheet 2 is radially tensioned. Further, on the area where the annular projections 6, 7 directly touch the sheet 2, a Teflon thin layer 32 is provided and an annular pressing member 30 having a thin iron plate 34 is provided just under the Teflon layer to press the inner and outer circumferential areas of the sheet 2. The iron layer 34 is heated by induction heating to promote adhesion between the substrate 1 and the recording sheet 2 with the adhesive 20 to complete the production of a recording disk 10. By this method, good adhesion is completed in a very short time and recording disks of high qualities can be efficiently obtd.

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention relates to an improvement in a method for manufacturing a recording disk, which is formed by adhering a recording sheet to at least one surface of a disc-shaped base having a recessed portion on its surface, such that the recessed portion forms a void. In particular, the present invention relates to a method of manufacturing a recording disk that is suitable for mass production. [0002] In recent years, there has been an increasing demand for higher density and higher capacity for recording disks used for recording information in computers and the like. [0003] Typical recording disks include floppy disks made by punching out a flexible disk sheet with a recording layer on a flexible support and inserting it into a jacket, and floppy disks made of less flexible materials such as aluminum. Rigid disks in which a recording layer is formed on a rigid base are known. [0004] Since floppy disks use a flexible support, they have excellent running durability, especially against sliding with the head, and the centerline average roughness of the recording surface is improved by surface treatment of the recording layer. Since it is possible to make the magnetic field Ra extremely low, high-density recording is possible. However, when the track density is increased in order to increase the recording capacity, there is a problem in that the head tends to be out of track due to thermal contraction of the support. [0005] On the other hand, rigid disks have a recording layer formed on a rigid base with little flexibility, making it difficult for the head to become misaligned due to heat shrinkage, etc. The problems have been resolved. [0006] In manufacturing a rigid disk, the surface of a substrate made of aluminum or the like is usually polished to improve its surface properties and enable high-density recording, and then a recording layer is formed thereon. However, it is difficult to reduce the surface roughness of the substrate surface to 0.1 μm or less in terms of center line average roughness Ra, and there is a limit to high-density recording. [0007] In addition, since the rigid disk has no flexibility in its base, there are manufacturing problems such as the inability to form a continuous recording layer, and the destruction of the recording layer due to large impact force when the head and the recording layer come into contact. However, there were some problems when using it. [00081 In recent years, in view of these problems with floppy disks and rigid disks, a flexible disk sheet with a recording layer on one side of a flexible support and a rigid disc-shaped base with wide annular recesses on both sides has been developed. A recording disk has been proposed in which the recess is attached so as to form a gap thereon. [0009] This type of recording disk has a rigid base like a rigid disk, so it is less prone to head misalignment due to heat shrinkage, etc. However, unlike a rigid disk, the recording surface is flexible. Therefore, even if the head contacts the recording surface, and even if high-density recording and reproduction is performed while the head is in sliding contact with the recording surface, the recording layer is unlikely to be destroyed. Furthermore, since the above-mentioned advantages of the floppy disk can be used as is, the disk has good surface properties and excellent running durability. In other words, this type of recording disk can be said to have the advantages of both floppy disks and rigid disks. [00101 The manufacturing method thereof is described, for example, in U.S. Patent No. 4,
No. 573,097. [00111] This manufacturing method consists of adhering a flexible disc-shaped recording sheet 2, the cross-section of which is schematically shown in FIG. 7, to a disc-shaped substrate 1, the cross-section of which is schematically shown in FIG. [00121 As shown in FIG. 7, the disc-shaped recording sheet 2 has a recording layer 3 provided on a flexible support 4,
It is punched out to match the shape of the disc-shaped base 1. [00131 The disc-shaped base 1 is configured such that a gap 5 is formed between the disc-shaped recording sheet 2 when the disc-shaped recording sheet 2 is bonded thereto. That is, as shown in FIG. 8, the disc-shaped base 1 has an inner circumferential annular convex portion 6 having a tapered surface that gradually becomes lower toward the inside and an outer circumferential annular convex portion 7 having a tapered surface that gradually decreases toward the outside. and an annular recess 8 is formed between them. Further, a hole 9 of a predetermined diameter is formed in the center of the disc-shaped base 1. [00141 As shown in an enlarged cross-section of the outer circumference in FIG. 6 and the tapered surface of the outer annular convex portion 7 via an adhesive, the recording disk 10 is formed. At this time, the disc-shaped recording sheet 2 is stretched radially on the disc-shaped base 1 so as not to sag. [00151 The 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. Even if the head comes into contact with the recording layer 3 during use of the recording disk 10, the gap 5 acts as a cushion, so that the recording layer 3 is prevented from being destroyed by the head. Moreover, as a result, the recording layer and the head are more likely to come into close contact with each other, and sliding movement suitable for high-density recording becomes possible. [0016] The most important step in the method of manufacturing such a recording disk, which requires precision, is the step of bonding the recording sheet to the disc-shaped base. In other words, it is necessary to apply a uniform and constant tension to the recording sheet adhered to the disc-shaped substrate, and to do this, it is necessary to apply an appropriate tension to the recording sheet during the adhesion process, but the adhesion If it takes a long time to complete, the characteristics of the recording medium may deteriorate due to the creep phenomenon of the flexible support, which may cause uneven tension such as local sag or wrinkles on the recording sheet. Sometimes. [0017] Various types of adhesives and bonding methods have been proposed in this bonding process. 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. In addition, Example 1 describes that after applying a room temperature curable epoxy adhesive, a disc-shaped base is pressed against a stretched recording sheet and cured. [0018] However, when a thermosetting adhesive is used, it takes a long time to harden, which reduces the mass productivity of recording disks. Furthermore, since the stretched recording sheet is left in a high-temperature environment, the flexible support of the recording sheet (polyethylene terephthalate, etc.) may creep, resulting in poor contact between the recording layer and the head. It may be the cause. In addition, there is a risk that dust etc. adhering to the recording layer will stick in a high-temperature environment and cause defects during data recording and playback, so a highly clean atmosphere is required and expensive equipment is required. Become. [0019] Even when a room temperature curing type poxy adhesive is used, it takes an extremely long time to harden, which reduces the mass productivity of recording disks. [00201 Japanese Patent Application Laid-Open No. 62-80828 discloses an example in which the edges are pressed together at 200° C. for 0.5 seconds using a solvent-free adhesive. However, no specific method has been disclosed, and in order to prevent the adverse effects of heating from reaching the recording sheet around the adhesive area and causing defects such as sagging and wrinkles in the recording sheet, high-temperature pressure is used. It was difficult to limit the effect to only the adhesive area. [0021] Furthermore, a method of completing the bonding process within a short time by irradiating radiation is disclosed in Japanese Patent Application Laid-Open No. 61-1518.
Although these methods are disclosed in Japanese Patent Application Laid-open No. 38 and Japanese Patent Application Laid-Open No. 62-80829, large-scale equipment is required for radiation irradiation, and there are drawbacks in terms of operability and production cost. [0022] As described above, in the adhesion process in the production of recording disks, it has been desired to reliably adhere the recording sheet onto the disk-shaped substrate within a short time at an appropriate production cost. Until now, there was no known method to satisfy this. [0023]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides a method for manufacturing a recording disk having a gap between a recording sheet and a disk-shaped base with excellent recording and reproducing characteristics. The purpose of this invention is to provide a manufacturing method that is highly suitable for mass production. [0024]

[Means for Solving the Problems] A method for manufacturing a recording disk according to the present invention includes bonding a disc-shaped recording sheet consisting of a flexible support and a recording layer provided on one surface of the disc-shaped base with an adhesive. When bonding while applying pressure using a pressure member via the disc, at least one of the disc-shaped base, the disc-shaped recording sheet, the pressure member, and the adhesive contains a substance that can be heated by induction. The invention is characterized in that the adhesion is promoted by induction heating. A typical recording disk manufactured by the present invention is a magnetic disk having a magnetic layer as a recording layer, but the present invention is not limited to magnetic disks, and includes phase change optical recording media, magneto-optical recording media, etc. It can be used to manufacture various recording disks such as. [0025] As the disk-shaped base, metals such as aluminum and aluminum alloys, glass, synthetic resins, filler-containing resins, and combinations thereof can be used. [00261 Disc-shaped bases made of synthetic resin can be manufactured in large quantities by injection molding, and are therefore generally inexpensive. [00271 Again. Crystalline polymers with heat resistance and non-grade polymers with a glass transition point of 80° C. or higher are preferred materials because they do not deform when stored at high temperatures. [0028] Specifically, polycarbonate, polyetherimide, polyphenyl sulfide, polyimide,
Preferred materials include polysulfone, polyacrylate, polyethersulfone, polyetheretherketone, and the like. [0029] Also, in order to reduce the value of the expansion coefficient of the disk-shaped base, metal oxides such as T i 02, Sin: and B
5 to 50% by weight of aSO4, glass fiber, etc. may be mixed. [00303 The disk-shaped recording sheet is formed of a material depending on the use of the recording disk. For example, when the recording disk is a magnetic disk, materials used in so-called floppy disks can be used. (00311 In this case, as a flexible support for the disc-shaped recording sheet, a plastic film such as polyethylene terephthalate is generally used, and biaxially oriented polyethylene terephthalate film (PET) is particularly preferred. In order to increase the recording density of the magnetic disk, it is preferable that the Ra (center roughness) of the surface on which the magnetic disk layer is provided is 0.1 μm or less. [0032] Also, when the recording layer is a magnetic layer, for example It can be formed by applying magnetic iron oxide or ferromagnetic alloy powder together with a binder, etc., or by using a paper deposition method such as vacuum evaporation, sputtering, or ion blasting, or a plating method. [00331 Disc-shaped substrate By making at least one of the adhesive, the flexible support, and the recording layer made of metal, induction heating can be preferably performed. [00341 Typical adhesives used in the present invention are: Although it is a hot melt adhesive, acrylic adhesives, thermosetting epoxy resins, etc. can also be used. [0035] As the base polymer of the hot melt adhesive, copolymerized polyester, polystyrene butadiene copolymer, etc. , acrylonitrile butadiene copolymer, polystyrene isoprene copolymer, ethylene butylene copolymer, polyisobutylene, polybutadiene, rubber resin such as butyl rubber, or polyethylene, polypropylene,
One or more types of polyolefin copolymers such as ethylene vinyl acetate copolymer and butyl acrylate vinyl acetate copolymer can be used. [0036] Tackifiers to be added to these base polymers include natural resins such as rosin, hydrogenated rosin, and rosin ester, and modified products thereof, aliphatic, ring family, aromatic, petroleum resins, and terpene resins, terpenes, There are phenolic resins, coumaron resins, etc., and softeners include process oil, paraffin oil, castor oil, polybutene,
Polyisoprene or the like is used. [0037] Additionally, additives such as fillers, anti-aging agents, and ultraviolet inhibitors can be added to the hot melt adhesive as necessary to improve heat resistance, weather resistance, etc. . [0038] These compounding ratios are base polymer 100
Based on the weight part, the tackifier is 100 to 600 parts by weight, and the softener is 0 to 100 parts by weight, but preferably has a softening point of 1.
40°C or less, more preferably 120°C or less,
Preferably, the melt viscosity is 1000 poise at 140°C.
Below, more preferably 1000poise at 160'C
Mix as follows. [0039] The adhesive includes, as an induction heatable substance,
For example, fine metal powder or fine ferromagnetic powder can be contained. [00401 As for the pressure member, it is desirable to use one having a shape that applies pressure only to the adhesive portion of the disc-shaped recording sheet and its vicinity, and does not affect the recording surface. [00411 By arranging a coil, wire mesh conductor, etc. in the pressure member or near the outside of the pressure member and applying a high frequency voltage thereto, it can be used as an induction heating means. At this time, it is preferable that the induction heating means be provided only at positions corresponding to the bonded portion and its vicinity so as not to affect the recording surface due to heating. [0042] Induction heating can be preferably performed by using iron as the suppressing surface of the pressure member. [00431 The induction heating temperature varies depending on the disc-shaped substrate, disc-shaped recording sheet, type of adhesive, and heating time, but is generally preferably 80 to 300°C, more preferably 10°C.
It is in the range of 0-200°C. [0044] Generally, it is preferable that the heating time is 0.5 seconds to 1 minute and the bonding pressure is 1 to 100 kg/cm2, but these may also vary depending on various conditions. [00451

[Operation] The principle of induction heating is that an induced current is generated in a conductor by electromagnetic induction, and heat is generated by eddy current and hysteresis loss. [00461 Thermal energy P [W/cm] generated in the electromagnetic material by induction heating is expressed by the following formula. [0047] [Equation 1] x:il conduction=il current [Acod:
Distance between electromagnetic material and coil: 1m [Qmlμ: Effective magnetic permeability γ: Specific resistance [Ω/cenl f: Frequency! lk[Hzl [0048] Thermal energy P1 per second generated by eddy currents is given by the following equation.
※※[o O491

[Equation 2] K: Proportional number N = Number of coils p: Electrical specific resistance of the conductor [00501 By using this principle of induction heating, it is easy to bond the disc-shaped recording sheet and the disc-shaped base. It can definitely be done in a short time. [00511] [Example] The present invention will be described in detail below with reference to the drawings. [00521] FIG. 1 is a sectional view showing a recording disk and a pressure member in an adhesion step of a recording disk manufacturing method according to an embodiment of the present invention. [0053] The recording disk 10 manufactured here is shown in FIG.
Since the structure is similar to that shown in FIGS. 7 to 9, the same reference numerals as those shown in FIGS. 7 to 9 are given to each member. [0054] As shown in FIG. 1, in this embodiment, the disc-shaped recording sheet 2 is placed on both sides of the disc-shaped base 1 on the tapered surface of the inner annular projection 6 and the tapered surface of the outer annular projection 7. The adhesive is bonded through the adhesive 20 while being pressed by a pressure member 30. [0055] FIG. 2 is an enlarged cross-sectional view of a part of the inner circumference of the recording disk and pressure member in FIG. 1. [0056] As shown in detail in FIG. 2, the pressure member 30 has a pressure surface formed by laminating a Teflon layer 32 and an iron layer 34. A coil 40 is embedded inside the convex portion of the pressure member 30 corresponding to the pressure surface. The pressure member 30 is shaped so as to press only the adhesive portion of the disc-shaped recording sheet 2 and its vicinity, and does not affect the recording surface. Further, the coil 40 is also provided only at a position corresponding to the adhesive portion and its vicinity, so that the recording surface is not affected by heating. [0057] FIG. 6 is a plan view showing the coil 40. Both ends A and B of the coil ** coil 40 are connected to a high frequency power source. [0058] In the embodiment shown in FIG. 2, coil 40
By applying a high frequency voltage to the iron layer 34, the iron layer 34 generates heat, and this heat is transmitted to the adhesive 20, thereby promoting the adhesive action of the adhesive 20. When the adhesive 20 is thermosetting, the adhesive action is promoted by curing, and when it is thermoplastic, it is plasticized. [00591 Figures 3.4.5 are sectional views showing enlarged portions of the inner circumferential portions of different embodiments. In these, parts similar to those in the embodiment shown in FIG. 2 are given the same reference numerals. [00601 In the embodiment shown in FIG.
' does not have the iron layer 34 as shown in FIG. Also,
The adhesive 20' is a double-sided adhesive film formed by providing an adhesive layer 26 on both sides of a support 22 with a conductive layer 24 interposed therebetween. Here, by applying a high frequency voltage to the coil 40, the conductive layer 24 generates heat, and this heat is transmitted to the adhesive layer 26, so that the adhesive action of the adhesive layer 26 is promoted. [00611 In the embodiment shown in FIG. 4, a metal disk-shaped base 1' and a metal thin film recording layer 3' are used, and these generate heat when a high frequency voltage is applied to the coil 40, and the adhesive 20 adhesion is promoted. [00621 In the embodiment shown in FIG.
contains fine metal powder 28. Application of a high frequency voltage to the coil 40 generates heat in the fine metal powder 28, promoting adhesion of the adhesive 20°. The same effect can be obtained by using a ferromagnetic fine powder, a flat dielectric fine powder, a low melting point conductive fine powder, etc. instead of the metal fine powder. [0063] [Example 1] Production of a disc-shaped 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 liquid having the following composition was coated on one side of the polyethylene terephthalate film. After coating so that the final thickness of the recording layer (magnetic layer) was 2 μm, it was dried, and the recording layer was surface-treated using a calendar to obtain a recording sheet (magnetic sheet). [0064] (Magnetic coating liquid) 7' Fez 03
300 ML parts VC-Ac (vinyl chloride-vinyl acetate copolymer, VYHHCCUC
(manufactured by Company C) 40 parts by weight epoxy resin (Epicoat 1001
Shell Chemical Co.) 40M parts Polyamide (Persamide 115 GM Co.) 20 parts by weight Methyl isobutyl ketone/Kizilol (2/1)
800 parts by weight Production of disk-shaped base Add glass fiber and inorganic filler to polyetherimide
A rigid disk-shaped substrate containing 0% of the compound was manufactured by injection molding. [0065] The shape of the disc-shaped base is as shown in FIG. 8, and the outer diameter r1 and inner diameter r2 of the disc-shaped base 1 are respectively *
*90mm and 20mm, length of inner annular convex part 6 1
1 and the length 12 of the outer circumferential annular convex portion 7 were both set to IM. Further, the thickness d of the disc-shaped base 1 was 2M, and the depth t of the concave portion 8 was 0.2 mm. [0066] Manufacture of recording disk □ Chemit solution KS-90 is applied as an adhesive to the tapered surfaces of the inner annular convex portion and the outer annular convex portion on both sides of the disc-shaped base.
3 (manufactured by Toshiku Co., Ltd.) was applied using a dispenser to a thickness of 15 μm and dried. [00671 Next, the disc-shaped recording sheet 2 is stretched radially using two annular members having an inner diameter larger than the outer diameter r of the disc-shaped base 1 (the equipment for this is not particularly shown). , was brought into contact with each tapered portion of the inner circumferential annular convex portion 6 and the outer circumferential annular convex portion 7. [0068] Furthermore, as shown in FIGS. 1 and 2, each tapered portion of the inner circumferential annular convex portion 6 and the outer circumferential annular convex portion 7 of the disk-shaped substrate has a convex portion on the surface to which the disc-shaped recording sheet is adhered. However, a thin Teflon layer 34 is placed on the surface that comes into direct contact with the recording sheet.
An annular pressure member 30 having an iron layer 32 with a thickness of 1.5 mm immediately below was used to press the outer and inner edges of the recording sheet. [0069] The radius of the annular pressure member 30 shown in FIG.
The relationship between r) and the radius (R) of the adhesive surface was as follows. [0070] r++<R++, r+2>R+z
, r2+<R2+, r,2>R22 At the same time as pressing, a high frequency voltage is applied for 10 seconds to the coil embedded in the convex part of the pressing member near the iron layer, and this** causes the iron layer 3
4 generates heat to promote adhesion between the disc-shaped base 1 and the disc-shaped recording sheet 2 by the adhesive 20, and the recording disc 1
I got 0. The high frequency voltage is 400kH2,3kV,
The heating temperature was 150°C. [00711 Example 2] Double-sided adhesive Meltron tape (manufactured by Diabond Co., Ltd.) punched into an annular shape to match the size of the adhesive surface was used instead of Chemit solution as the adhesive. this is,
The support has a material that can be heated by induction. [0072] The support for the disc-shaped recording sheet has a thickness of 3
A polyimide film with a thickness of 2 μm and a width of 120 am was used. [0073] Also, as a pressure member, the iron layer 32 from FIG.
A structure other than that shown in FIG. 3, a part of which is shown on an enlarged scale, was used, and the high frequency voltage was applied for 5 seconds and the applied voltage was 4 kV. [0074] A recording disk was obtained under the same conditions as in Example 1 except for the following conditions. [0075] [Comparative Example 11] An adhesive having the following composition was used. [0076] Epoxy resin (Epicote 828 manufactured by Shell Co., Ltd.)
100 parts triethylamine
Part 5 After applying this adhesive to a thickness of 1101L on the tapered surfaces of the inner annular convex portion and the outer annular convex portion on both sides of the disc-shaped substrate, place the recording sheet and perform induction heating. It was left at 60°C for 5 hours. [0077] A recording disc was obtained under the same conditions as in Example 1 except for the above conditions. [0078] [Comparative Example 2] An adhesive having the following composition was used. [0079] Styrene butadiene copolymer
100 parts methyl ethyl ketone
300 parts of this adhesive was applied to the tapered surfaces of the inner annular convex portion and the outer annular convex portion on both sides of the disc-shaped base so that the dry film thickness was 1101z,
After drying at 100°C for 10 seconds, a recording sheet was placed and left at 60°C for 5 hours without induction heating. [00801 A recording disc was obtained under the same conditions as in Example 1 except for the following conditions. [00811 Table 1 shows the evaluation results of the samples thus obtained. [0082] [Table 1] [0083] The adhesion state was evaluated by pasting Mylar tape on the recording sheet and peeling it off at 180 degrees 50 times, and observing the state of peeling at the edges.
☆# (0084) P S T (Penetr
ation 5tiffness) is the force in g/mm that is applied when the tip of a needle-like probe (spherical with r = 3.2 parts m) is pushed perpendicularly into the recording sheet, and the adhesion condition of the recording sheet ( tension) can be easily quantified. In magnetic sheets, there is a correlation between the PST and the head/media interface; in particular, the output level increases as the PST increases within a certain range, saturates when it exceeds a certain range, and decreases when it exceeds the upper limit. It is known that there are cases where [00851 Output is expressed as a relative value (in dB) with respect to the reference disk. [0086] Defect locations were evaluated based on the number of missing pulses. [0087]

[Effects of the Invention] In the method for manufacturing a recording disk according to the present invention, since the adhesion between the disk-shaped base and the disk-shaped recording sheet is promoted by induction heating, good adhesion can be completed in an extremely short time. , it is possible to efficiently mass-produce recording discs of good quality. [0088] Again. If a film-like double-sided adhesive is used as the adhesive, the process will be significantly simplified compared to the method of applying a solvent-based adhesive in advance and then applying heat bonding.
Moreover, the effect is obtained that there are no equipment problems or safety problems associated with the use of solvents.

[Brief explanation of the drawing]

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

FIG. 2 is an enlarged cross-sectional view of a part of the inner circumference of the recording disk and pressure member shown in FIG. 1;

FIG. 3 is an enlarged sectional view showing a part of the inner circumference of a recording disk and a pressure member in another embodiment.

FIG. 4 is a sectional view showing an enlarged part of the inner circumference of a recording disk and a pressure member in another embodiment.

FIG. 5 is a sectional view showing an enlarged part of the inner circumference of a recording disk and a pressure member in another embodiment.

FIG. 6 is a plan view showing a coil used in one embodiment of the present invention.

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

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

[Fig. 9] A cross-sectional view showing an enlarged part of the outer circumference of the recording disk shown in Fig. 1.

[Explanation of symbols]

1 Disk-shaped base 2 Disk-shaped recording sheet 3 Recording layer 4 Flexible support 5 Gap 6 Inner circumferential annular convex part 7 Outer circumferential annular convex part 8 Annular recess 9 holes 10 Recording disc 20 Adhesive 22 Support 24 Conductive layer 26 Adhesive layer 28 Fine metal powder 30 Pressure member 32 Teflon layer 34 Iron layer 40 Coil

[Figure 3]

[Procedural amendment]

[Submission date] November 26, 1991

[Procedural amendment 1]

[Name of document to be amended] Specification

[Correction target item name] 0003 [Correction method] Change

[Correction details]

[0003] Typical recording disks include floppy disks made by punching out a flexible sheet with a recording layer on a flexible support and inserting it into a jacket, and rigid discs with less flexibility such as aluminum. Rigid disks in which a recording layer is formed on a substrate are known.

[Procedural amendment 2]

[Name of document to be amended] Specification

[Correction target item name] 0006 [Correction method] Change

[Correction details]

[0006] In manufacturing a rigid disk, the surface of a substrate made of aluminum or the like is usually polished to improve its surface properties and enable high-density recording, and then a recording layer is formed thereon. However, it is difficult to reduce the surface roughness of the substrate surface to 0.01 μm or less in terms of center line average roughness Ra, and there is a limit to high-density recording.

[Procedural amendment 3]

[Name of document to be amended] Specification

[Correction target item name 10031 [Correction method] Change

[Correction details]

[00311] In this case, a plastic film such as polyethylene terephthalate is generally used as the flexible support for the disc-shaped recording sheet, and biaxially oriented polyethylene terephthalate film (PET) is particularly preferred. Other materials include polyimide, polyethylene naphthalate (PE
Materials such as N), polyethylene sulfide (PPS), etc. can also be used. Further, in order to increase the recording density of the magnetic disk, it is preferable that the Ra (center roughness) of the surface on which the recording layer (magnetic layer) is provided is 0.1 μm or less.

Claims (5)

[Claims] [Claim 1] A disc-shaped base having an inner circumferential annular convex portion having a tapered surface that gradually becomes lower toward the inside and an outer circumferential annular convex portion having a tapered surface that gradually decreases toward the outside is prepared, A disc-shaped recording sheet consisting of a flexible support and a recording layer provided on one surface of the disc-shaped recording sheet is prepared, and the disc-shaped recording sheet is attached to the disc-shaped base with the inner and outer peripheral parts of the flexible support. In the method for manufacturing a recording disk, the disk-shaped base plate is bonded to the tapered surface of the inner circumferential annular convex portion and the tapered surface of the outer circumferential annular convex portion with an adhesive while applying pressure using a pressure member. . A manufacturing method characterized in that at least one of the disk-shaped recording sheet, the pressure member, and the adhesive contains a substance that can be heated by induction, and the adhesion is promoted by induction heating. 2. The manufacturing method according to claim 1, wherein the adhesive contains fine metal powder. 3. The manufacturing method according to claim 1, wherein the adhesive contains ferromagnetic fine powder. 4. The manufacturing method according to claim 1, wherein at least one of the disk-shaped base, the flexible support, and the recording layer is made of metal. 5. The manufacturing method according to claim 1, wherein the pressing surface of the pressing member is made of iron.