JPH04330624A - Production of recording disk - Google Patents

Abstract

PURPOSE:To allow mass production of the recording disk having excellent recording and reproducing characteristics in the process for producing the recording disk. CONSTITUTION:The adhesion of a disk-shaped recording sheet 2 consisting of a flexible base and a recording layer provided on one surface thereof and the tapered surfaces of an annular projecting part 6 on the inner peripheral side and projecting part 7 on the outer peripheral side of a disk-shaped substrate 1 is accelerated by high-frequency induction heating or microwave heating at the time of adhering the above-mentioned sheet and tapered surfaces while pressurizing the same by using pressurizing members 30.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to an improvement in a method for manufacturing a recording disk in which a recording sheet is adhered to at least one surface of a disc-shaped base having a concave portion on its surface so that the concave 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

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

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 disks with little flexibility such as aluminum. Rigid disks in which a recording layer is formed on a substrate are known.

Since a floppy disk uses a flexible support, it has 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 Ra can be made 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.

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 misalign due to heat shrinkage, etc. The problems have been resolved.

[0006] In manufacturing rigid disks, usually
The surface of a substrate made of aluminum or the like is 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.

[0007] In addition, rigid disks have manufacturing problems such as the inability to form a continuous recording layer due to the lack of flexibility in the base, and problems such as destruction of the recording layer due to large impact force when the head and recording layer come into contact. However, there were some problems when using it.

In recent years, in view of these problems with floppy disks and rigid disks, a flexible disk sheet consisting of a recording layer provided on one side of a flexible support and a rigid disk-shaped base with wide annular recesses provided on both sides have been developed. A recording disk has been proposed in which the concave portion is attached on top of the disk so as to form a gap.

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.

The manufacturing method is described, for example, in US Pat. No. 4,
No. 573,097.

This manufacturing method consists of adhering a flexible disc-shaped recording sheet 2, the cross-section of which is schematically shown in FIG. 6, to a disc-shaped substrate 1, the cross-section of which is schematically shown in FIG.

As shown in FIG. 6, the disc-shaped recording sheet 2 has a recording layer 3 provided on a flexible support 4.
After being adhered to the disc-shaped base 1, the excess portion is cut off to match the shape of the disc-shaped base 1.

The disc-shaped base 1 is constructed so 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. 7, 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.

As shown in FIG. 8, which shows an enlarged cross-section of the outer peripheral part, the recording layer 3 of the disc-shaped recording sheet 2 is placed on the front side, and the flexible support 4 is placed on the inner peripheral side annular convexity of the disc-shaped base 1. The recording disk 10 is formed by adhering to the tapered surface of the portion 6 and the tapered surface of the outer annular convex portion 7 via an adhesive. At this time, the disc-shaped recording sheet 2 is stretched radially on the disc-shaped base 1 so as not to sag.

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. 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.

The most important step in the method of manufacturing such a recording disk, which requires precision, is the step of adhering 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.

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. 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.

However, when a thermosetting adhesive is used, it takes a long time to harden, which lowers the mass productivity of recording disks. Furthermore, since the stretched recording sheet is left in a high-temperature environment, the recording sheet's flexible support (polyethylene terephthalate, etc.) may creep, causing a poor interface between the recording layer and the head. It may become. 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.

Even when a room temperature curing epoxy adhesive is used, it takes an extremely long time to cure, which reduces the mass productivity of recording disks.

[0020] JP-A-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 Laid-Open No. 61-1518.
These methods are disclosed in Japanese Patent Application Laid-open No. 38, Japanese Patent Application Laid-Open No. 62-80829, etc., but 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 discs, it has been desired to reliably adhere the recording sheet onto the disc-shaped base within a short period of 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] The method for manufacturing a recording disk of the present invention is such that when a disc-shaped recording sheet is bonded to a disc-shaped substrate while being pressed using a pressure member, the above-described method is performed using high-frequency dielectric heating or microwave heating. It is characterized by promoting adhesion.

[0025] High frequency dielectric heating and microwave heating are based on the same principle, but the latter is characterized by a significantly higher frequency.

High-frequency dielectric heating can be performed by placing an electrode near the object to be heated and applying a high-frequency voltage to the electrode. Thermal energy generated by high frequency dielectric heating is expressed by the following equation.

[0027]

[Equation 1] P=5/9・ε・tanδ・f・(V/d)2 ×
10-12 [W/cm3] ε: Dielectric constant tan δ of adherend or adhesive: Power factor f: Frequency [Hz] V: Voltage [V] d: Electrode spacing [cm] Microwave heating This can be done by emitting microwaves from a magnetron into a cavity. The cavity is made of a material that reflects microwaves well and has a certain degree of heat resistance and rigidity. Glass and plastic are undesirable because they allow microwaves to pass through them, but metal materials are preferred. For example, stainless steel is a practically preferred cavity material.

Thermal energy generated by microwave heating is expressed by the following equation.

[0029]

[Formula 2] P=K・ε・tanδ・f・E2・ρ・V[W]K
: Constant ε : Permittivity of adhesive tan δ : Power factor f : Frequency [Hz] E : Electric field strength [V/cm] ρ
: Specific gravity V : Volume [cm3] According to the present invention, by using high-frequency dielectric heating or microwave heating, the disc-shaped recording sheet and the disc-shaped substrate can be easily and reliably bonded in a short time. In particular, since thermal bonding can be performed in a short time under tension, it is possible to prevent creep of disc-shaped recording sheets and increase mass production.Also, since the heating area can be concentrated on the bonded area, defects can be avoided. can be reduced. Furthermore, when microwave heating is used, there is a high degree of freedom in designing the processing machine used in the bonding process, and its structure can be simplified, which is advantageous in terms of mass production and equipment costs.

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, but can also be applied to phase change optical recording media, optical It can be used to manufacture various recording disks such as magnetic recording media.

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

[0032] Disc-shaped bases made of synthetic resin can be manufactured in large quantities by injection molding, and are therefore generally inexpensive.

[0033] In addition, heat-resistant crystalline polymers and amorphous polymers with a glass transition point of 80°C or higher are preferred materials because they do not deform when stored at high temperatures.

Specifically, polycarbonate, polyetherimide, polyphenyl sulfide, polyimide,
Preferred materials include polysulfone, polyacrylate, polyethersulfone, polyetheretherketone, and the like.

Furthermore, in order to reduce the value of the expansion coefficient of the disk-shaped substrate, metal oxides such as TiO2 and SiO2, Ba
SO4, glass fiber, etc. may be mixed in an amount of 5 to 50% by weight.

[0036] The disc-shaped recording sheet is made of a material depending on the use of the recording disc. For example, when the recording disk is a magnetic disk, materials used in so-called floppy disks can be used.

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, but polyimide, polyethylene Phthalate (PEN),
Polyethylene sulfide (PPS) and the like can also be used. Also, the radius of the surface on which the recording layer (magnetic layer) is provided is
It is preferable that a (center roughness) is 0.01 μm or less in order to increase the recording density of the magnetic disk.

If the recording layer is a magnetic layer, for example, magnetic iron oxide or ferromagnetic alloy powder may be coated with a binder, vapor deposition methods such as vacuum evaporation, sputtering, ion plating, plating methods, etc. It can be formed by using

Generally, it is preferable to provide an adhesive between the disc-shaped recording sheet and the disc-shaped base for adhesion.
If the dielectric loss coefficient, expressed as the product of permittivity (ε) and power factor (tanδ), is large for both the disk-shaped recording sheet and the disk-shaped substrate, high-frequency dielectric heating can be used to bond both without using an adhesive. It is possible to glue. For example, when the disc-shaped recording sheet and disc-shaped base are formed of vinyl chloride, methacrylic resin, phenol resin, urea resin, melamine resin, polyurethane, etc., the adhesive can be omitted. In particular, when an ordinary floppy disk having magnetic layers on both sides is used as the disc-shaped recording sheet, an adhesive effect can be obtained by the polyurethane contained in the magnetic layer. When no adhesive is used, the process, equipment, and materials can be significantly simplified.

When an adhesive is used, it is preferable that its dielectric loss coefficient is larger than that of the disc-shaped recording sheet and the disc-shaped substrate, and it is preferable that the dielectric loss coefficient is 0.05 or more. .

[0041] When heating the adhesive with microwaves, the disk-shaped base should be made of a material with a small dielectric loss coefficient that transmits most of the microwaves, or a metal that reflects most of the microwaves. is preferred. Further, in this case, it is preferable to use a material with a small dielectric loss coefficient that allows microwaves to easily pass through the disc-shaped recording sheet.

As the adhesive, a liquid adhesive may be applied to the adhesive surface of at least one of the disc-shaped recording sheet and the disc-shaped base, or a concentric double-sided adhesive tape or the like may be used to bond the disc-shaped recording sheet. It may be arranged between the adhesive part and the adhesive part of the disc-shaped base. The use of double-sided adhesive tapes has the advantage that the process is simplified and there are no equipment or safety problems associated with the use of solvents.

[0043] In order to enhance the adhesion effect, a groove or a hole may be provided in the adhesive portion of the disc-shaped base, and the adhesive may be placed in the groove or hole. Additionally, one or both of the bonding surfaces may be subjected to physical surface treatment such as corona discharge, glow discharge, flame treatment, etc. to facilitate bonding.

[0044] Typical adhesives used in the present invention are hot melt adhesives, but acrylic adhesives, thermosetting epoxy resins, and the like can also be used.

As the base polymer for the hot melt adhesive, rubbers such as copolymerized polyester, polystyrene butadiene copolymer, acrylonitrile butadiene copolymer, polystyrene isoprene copolymer, ethylene butylene copolymer, polyisobutylene, polybutadiene, and butyl rubber are used. resin, 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.

Tackifiers to be added to these base polymers include natural resins such as rosin, hydrogenated rosin, and rosin esters, modified products thereof, aliphatic, alicyclic, aromatic, petroleum resins, terpene resins, and terpene resins. , phenolic resin, coumaron resin, etc., and softeners include process oil, paraffin oil, castor oil, polybutene,
Polyisoprene or the like is used.

[0047] Furthermore, additives such as fillers, anti-aging agents, and ultraviolet light inhibitors can be added to the hot melt adhesive to improve heat resistance, weather resistance, etc., if necessary.

These compounding ratios are base polymer 100
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 140°C or lower, more preferably 120°C or lower, and preferably has a melt viscosity of 140°C or lower. 1000p at °C
oise or less, more preferably 1000p at 160℃
oise Mix so that it becomes the following.

Furthermore, heat generation can be promoted by mixing a substance with a very large dielectric loss coefficient into the adhesive. For example, barium titanate, zinc oxide, magnesium oxide, carbon black, water, etc. can be mixed for this purpose, but the amount must be suppressed to an extent that does not cause a decrease in adhesive strength.

[0050] It is desirable to use a pressure member 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.

[0051] When high frequency dielectric heating is performed, an electrode is provided on the pressure member and a high frequency voltage is applied thereto, thereby making it possible to use the pressure member as a dielectric heating means. If the pressure member is made of a conductive material, it can be used as an electrode as it is.

[0052] When performing microwave heating, it is preferable to use a material with a small dielectric loss coefficient that allows microwaves to easily pass through the pressurizing member.

[0053] The temperature of the adhesive or adhesive part during high-frequency dielectric heating or microwave heating varies depending on the temperature of the disc-shaped substrate,
Although it varies depending on the disc-shaped recording sheet, the type of adhesive, and the heating time, the temperature is generally preferably in the range of 80 to 300°C, more preferably 100 to 200°C.

Generally, it is preferable that the heating time is 1 second to 3 minutes and the bonding pressure is 1 to 100 kg/cm2.
These may also change depending on various conditions.

[0055] After bonding the disc-shaped base and the disc-shaped recording sheet, it is also possible to perform heat treatment in order 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 and below 120°C, and the time may be set between 24 hours and about 3 seconds depending on the temperature. After heat treatment, cool to room temperature.

[0056]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

Since the recording disk 10 manufactured in each of the following examples has the same structure as that shown in FIGS. 6 to 8, each member thereof has the same structure as that shown in FIGS. with reference number.

As shown in FIG. 1, in this embodiment, the pressure member 30 has an annular convex portion and is made of a material that also functions as an electrode. The disc-shaped recording sheet 2, which has been stretched radially on both sides, is applied to the tapered surface of the inner circumferential annular convex portion 6 and the tapered surface of the outer circumferential annular convex portion 7 via a pressure member 30 via an adhesive 20.
Adhesion is applied while applying pressure using the annular convex portion. At this time, a high frequency voltage is applied to the pressure member 30. adhesive 2
When the dielectric loss coefficient of 0 is sufficiently larger than the dielectric loss coefficients of the disc-shaped substrate 1 and the disc-shaped recording sheet 2, internal self-heating due to dielectric heating is concentrated in the adhesive 20. The adhesive action is promoted by curing when the adhesive 20 is thermosetting, and by plasticization when it is thermoplastic.

FIG. 2 is an enlarged cross-sectional view of a part of the outer periphery of the recording disk and pressure member in FIG. 1. As shown in FIG. As shown in detail in FIG. 2, the pressure member 30 is shaped so as to press only the adhesive portion of the disc-shaped recording sheet 2 and the vicinity thereof, without affecting the recording surface.

FIG. 3 is an enlarged sectional view similar to FIG. 2 of another embodiment. Here, parts similar to those in the embodiment shown in FIG. 2 are given the same reference numerals. In the embodiment shown in FIG. 3, the adhesive 20' is a concentric double-sided adhesive film comprising a support 22 and adhesive layers 24 on both sides.

FIG. 4 is a sectional view similar to FIG. 1 in another embodiment. Here, the disc-shaped recording sheet 2, which is stretched radially on both sides of the disc-shaped base 1, is applied to the tapered surface of the inner annular protrusion 6 and the tapered surface of the outer annular protrusion 7 without using an adhesive. Bonding is performed while applying pressure using the annular convex portion of the pressure member 30. If the dielectric loss coefficients of the disc-shaped substrate 1 and the disc-shaped recording sheet 2 are large, such a configuration is also possible.

Note that in these figures, a jig for applying tension to radially stretch the disc-shaped recording sheet 2 is not particularly shown.

FIG. 5 is a sectional view similar to FIG. 1 in an embodiment using a microwave heating device. Here, the disk-shaped recording sheet 2 is stretched in advance using a jig (not shown) to apply tension, and the tension maintaining jig 4 is used together with the pressure member 30'.
0, and this tension is held by a tension holding jig 40. Both the pressure member 30' and the tension holding jig 40 are preferably made of a material that transmits microwaves, for example, an engineering plastic material such as polyetherimide (PEI). Since the tension holding jig 40 can be made much smaller than the jig used to initially stretch the disc-shaped recording sheet 2, it is advantageous in terms of space efficiency when used inside a cavity.

The recording disk 10 is placed on the platform 60 in the metal cavity 50 while being pressed by the pressure member 30' and the tension holding jig 40, and the microwave 80 is emitted from the antenna 75 of the magnetron 70. is emitted to promote the adhesive action of the adhesive 20 by microwave heating. The platform 60 is preferably formed of a material that transmits microwaves, but may also be formed of a net-like metal or the like. There is no particular restriction on its shape as long as it can accommodate the object to be heated and sufficiently transmits microwaves.

Microwave 8 emitted from the magnetron
0 is reflected on the wall surface of the cavity 50 and efficiently contributes to heating the adhesive. From this point of view, it is better to arrange the recording disk 10 at some distance from the cavity wall surface, but the specific arrangement is determined as appropriate depending on the jig and the disk diameter.

A stirrer 90 is provided in the cavity 50 to stir the atmosphere inside. Starra 90
The use of is effective in equalizing the temperature around the heated bonding part.

In this embodiment as well, the adhesive 20 can have a form as shown in FIGS. 2 and 3. However, in the case of microwave heating, the high-frequency energy fills the entire cavity, and unlike high-frequency dielectric heating, the structure does not concentrate the high-frequency energy. Considering the adverse effects of heating on the disc-shaped recording sheet 2, it is not desirable to increase the dielectric loss coefficient of the disc-shaped base 1 and the disc-shaped recording sheet 2 and omit the adhesive as shown in FIG.

[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.
After coating one side of the magnetic coating liquid with the following composition so that the final recording layer (magnetic layer) has a thickness of 2 μm, it is dried, and then the surface of the recording layer is treated with a calender. A sheet (magnetic sheet) was obtained. (Magnetic coating liquid) γ-Fe2 O3

300 parts by weight PVC-Ac


(vinyl chloride-vinyl acetate copolymer, V
YHHCC (manufactured by UCC) 40 parts by weight Epoxy resin (Epicote 1001 manufactured by Shell Chemical Co.) 40 parts by weight
Polyamide (Versamide 115 manufactured by GM)
20 parts by weight Methyl isobutyl ketone/xylol (2/1) 800 parts by weight Production of disc-shaped base Add glass fiber and inorganic filler to polyetherimide 4
A rigid disk-shaped substrate containing 0% of the compound was manufactured by injection molding.

The shape of the disc-shaped base 1 is as shown in FIG. 6, and the outer diameter r1 and inner diameter r2 of the disc-shaped base 1 are 90 mm and 20 mm, respectively, and the length l of the inner annular convex portion 6.
1 and the length l2 of the outer circumferential annular convex portion 7 are both 1 m.
It was set as m. Further, the thickness d of the disc-shaped base 1 was 2 mm, and the depth t of the annular recess 8 was 0.2 mm.

Manufacturing of a recording disk Chemit solution KS-903 was 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 substrate.
(manufactured by Toray Industries, Inc.) was applied using a dispenser to a thickness of 15 μm and dried.

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). ), and was brought into contact with each tapered portion of the inner circumferential annular convex portion 6 and the outer circumferential annular convex portion 7.

Further, as shown in FIGS. 1 and 2, an annular projection is formed on the tapered portion of the inner annular projection 6 and the outer annular projection 7 of the disc-shaped substrate on the surface to which the disc-shaped recording sheet is adhered. The outer peripheral end and the inner peripheral end of the recording sheet were pressed using a pressure member 30 having the following.

The relationship between the radius (r) of the pressure member 30 and the radius (R) of the adhesive surface shown in FIG. 1 was as follows. However, the difference in radius between the pressure member and the adhesive surface was small. r11<
R11, r12>R12, r21<R21, r22>R
At the same time as pressing 22, a high frequency voltage was applied to the pressure member 30 for 20 seconds to promote adhesion between the disc-shaped base 1 and the disc-shaped recording sheet 2 by the adhesive 20 by dielectric heating, thereby obtaining a recording disk 10. The applied high frequency voltage was 40.6MH
z, and the pressurizing pressure was 3 kgf/cm2.

[Example 2] Instead of the Chemit solution as an adhesive, a double-sided adhesive Chemit film adhesive (KF-2000 manufactured by Toray Industries, Inc.) was punched into a circular shape according to the size of the adhesive surface. A recording disk was obtained under the same conditions as in Example 1 except that the configuration shown in FIG. 3 was adopted.

[Example 3] As the flexible support of the disc-shaped recording sheet, aramid with a large loss coefficient was used instead of polyethylene terephthalate film, and as the disc-shaped base, glass fiber, polyetherimide, and polyetherimide were used. Instead of using a melamine resin containing 40% inorganic filler, a melamine resin with a large dielectric loss coefficient was used, no adhesive was used, the structure was as shown in Figure 4, and the pressure was 7 kgf/
A recording disk was obtained under the same conditions as in Example 1 except that the diameter was changed to cm2.

[Example 4] Using the microwave heating device shown in FIG. 5, the antenna 6 of the magnetron 60 was heated simultaneously with pressing.
5 to generate a microwave with a frequency of 2450 MHz and an output of 740 W, and the adhesive 2 was heated by microwave heating.
A recording disk was obtained under the same conditions as in Example 1, except that adhesion between the disk-shaped substrate 1 and the disk-shaped recording sheet 2 was promoted by the adhesive agent 0.

[Example 5] Instead of the Chemit solution as an adhesive, a double-sided adhesive Chemit film adhesive (KF-2000 manufactured by Toray Industries, Inc.) was punched into an annular shape according to the size of the adhesive surface. A recording disk was obtained under the same conditions as in Example 4, except for having the configuration shown in FIG.

[Comparative Example 1] An adhesive having the following composition was used. Epoxy resin (Epicote 828 manufactured by Shell Co., Ltd.) 100 parts Triethylamine

Part 5: After applying this adhesive to a thickness of 10 μm 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 a recording sheet on it,
60 minutes without high-frequency dielectric heating or microwave heating.
It was left at ℃ for 5 hours. A recording disk was obtained under the same conditions as in Example 1 except for the above conditions.

[Comparative Example 2] An adhesive having the following composition was used. Styrene butadiene copolymer

100 parts methyl ethyl ketone

300 parts of this adhesive was applied to the tapered surfaces of the inner and outer annular protrusions on both sides of the disc-shaped base so that the dry film thickness was 10 μm.
After drying at ℃ for 10 seconds, the recording sheet was placed and heated at 60℃ without high-frequency dielectric heating or microwave heating.
I left it for 5 hours. A recording disk was obtained under the same conditions as in Example 1 except for the above conditions.

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

[0082]

[Table 1]

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] PST
ffness) is the tip of the needle-like probe (r=3.2
This is the force applied when a spherical (mm) is pressed perpendicularly into a recording sheet in units of g/mm, and is an index of adhesive strength that can easily quantify the adhesion (tension) of a recording sheet. There is one. According to the knowledge obtained so far, in the case of flexible magnetic sheets, PST
There is a correlation between the measured value and the problem of the head/media interface, and in particular, the output level increases as the PST increases within a certain range, saturates after a certain range, and decreases when the upper limit is exceeded. It is known that there are cases where According to the inventor's experimental results, the desirable value of PST is 30 to 300 g/mm, more preferably 100 g/mm.
It has been revealed that it is in the range of ~200g/mm2.

The output was expressed as a relative value (in dB) with respect to the reference disk.

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, the adhesion between the disk-shaped substrate and the disk-shaped recording sheet is promoted by high-frequency dielectric heating or microwave heating, so that good adhesion can be achieved in an extremely short time. It is possible to efficiently mass-produce recording discs of good quality.

Furthermore, if a film-like double-sided adhesive is used as the adhesive, the process is significantly simplified compared to a method in which a solvent-based adhesive is applied in advance and then heat bonded.
Moreover, the effect is obtained that there are no equipment problems or safety problems associated with the use of solvents.

Furthermore, when high-frequency dielectric heating is used, if the dielectric loss coefficient of the disc-shaped substrate and disc-shaped recording sheet is large, it is possible to bond them together without using an adhesive, and it is possible to bond them together without using an adhesive. In addition to this effect, it is also possible to reduce raw material costs.

[Brief explanation of drawings]

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 outer periphery of the recording disk and pressure member shown in FIG.

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

FIG. 4 is a cross-sectional view showing a recording disk and a pressure member in an adhesion step of a recording disk manufacturing method in another embodiment.

FIG. 5 is a sectional view showing a recording disk and a pressure member in an adhesion step of a recording disk manufacturing method in another embodiment.

FIG. 6 is a sectional view showing a recording sheet used in one embodiment of the present invention.

FIG. 7 is a sectional view showing a recording disk manufactured according to an embodiment of the present invention.

[Fig. 8] A cross-sectional view showing an enlarged part of the outer circumference of the recording disk shown in Fig. 7.

[Explanation of symbols]

1 Disk-shaped base 2 Disk-shaped record sheet 3 Recording layer 4 Flexible support 5 Gap 6　Inner peripheral side annular convex part 7　Outer circumferential side annular convex part 8 Annular recess 9 holes 10 Recording disc 20 Adhesive 22 Support 24 Adhesive layer 30 Pressure member 40 Tension holding jig 50 Cavity 60 Mounting stand 70 Magnetron 75 Antenna 80 Microwave 90 Starla

Claims (4)

[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 outer circumferential side 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 inner and outer peripheral parts of the flexible support of the disc-shaped recording sheet are attached to the disc-shaped base. In a method for manufacturing a recording disk, the tapered surface of the inner circumferential annular convex portion and the tapered surface of the outer circumferential annular convex portion are bonded while being pressed using a pressure member,
A method for manufacturing a recording disk, characterized in that the adhesion is promoted by high-frequency dielectric heating or microwave heating. 2. The method of manufacturing a recording disk according to claim 1, wherein the disk-shaped recording sheet and the disk-shaped base are bonded together with an adhesive. 3. The method of manufacturing a recording disk according to claim 2, wherein the dielectric loss coefficient of the adhesive is larger than the dielectric loss coefficient of the disc-shaped recording sheet and the disc-shaped base. 4. The dielectric loss coefficient of the adhesive is 0.05.
3. The method of manufacturing a recording disk according to claim 2, wherein the method is as follows.