JPH05314473A - Manufacture of recording disk - Google Patents

Abstract

PURPOSE:To realize mass-production of a recording disk having excellent recording and playback characteristics at a low cost in a method of manufacturing a recording disk having a gap between a recording sheet and a disk-shaped rigid substrate. CONSTITUTION:The internal circumference and external circumference of the surface not provided with a recording layer are temporarily fixed, under the condition that a recording sheet 2 is extended radially, to a circular projected portion 6 in the side of internal circumference and the projected portion 7 in the side of the external circumference of a disk-shaped rigid substrate 1. Under this temporary fixing condition, inspection for defect is carried out. For those having passed the inspection for defect, the recording sheet 2 is clamped to the circular projected portion 6 in the side of internal circumference and to the circular projected portion 7 in the side of external circumference under the substantially same extending condition as the temporary fixing condition and under the relative positional relationship.

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 disc-shaped rigid substrate having a recess on its surface so that the recess becomes a void. In particular, the present invention relates to a method for manufacturing a recording disk excellent in suitability for mass production.

[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. Had problems in use.

In recent years, in view of the problems of these floppy disks and rigid disks, a flexible disk sheet having a recording layer provided on one surface of a flexible support has a disk-shaped rigid base 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 consists of adhering a flexible recording sheet 2 of which the cross section is shown in FIG. 4 to a disc-shaped rigid base 1 of which the cross section is shown in FIG.

As shown in FIG. 4, the recording sheet 2 has a recording layer 3 provided on a flexible support 4 and is adhered to the disc-shaped rigid base 1 and then the disc-shaped rigid base 1 is formed. The extra part is cut out to fit the shape.

The disc-shaped rigid substrate 1 is constructed so that a gap 5 is formed between the recording sheet 2 and the recording sheet 2 when they are adhered to each other. That is, as shown in FIG. 5, the disc-shaped rigid 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 concave portion 8 therebetween. Are formed. Further, a hole 9 having a predetermined diameter is formed in the central portion of the disc-shaped rigid base 1.

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

A gap 5 between the disc-shaped rigid base 1 and the recording sheet 2 is formed at a position corresponding to the annular recess 8 of the disc-shaped rigid base 1. When the recording disk 10 is used, even if the head comes into contact with the recording layer 3, the gap 5 serves as a cushion, which prevents the recording layer 3 from being destroyed by the head. Also,
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 such a recording disk manufacturing method, it is necessary to apply a uniform and constant tension to the recording sheet adhered on the disc-shaped rigid base. For that purpose, the recording sheet is adhered to the recording sheet in the adhering step. It is necessary to apply an appropriate tension.

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 disc-shaped rigid base is pressed against the recording sheet in the stretched state to be cured.

One of the methods for adhering the recording sheet to the outer peripheral convex portion and the inner peripheral convex portion of the disc-shaped rigid base while stretching it is described in JP-A-62-121930. This is a method of using a pressing jig having an annular convex portion and a disc-shaped rigid base having an annular groove portion outside the outer peripheral convex portion and inside the inner peripheral convex portion. The recording sheet is sandwiched between the recording sheet and the recording sheet, and the annular convex portion of the pressing jig is pushed into the annular groove portion of the disc-shaped rigid base, whereby the recording sheet is attached while being stretched. After sticking, the pressing jig is removed, but the disc-shaped rigid base becomes a component of the recording disk as it is. Another method of stretching and adhering is described in JP-A-3-86920. This consists of tensioning a recording sheet on a flat surface with a uniform tension, and then sticking the recording sheet to the outer peripheral convex portion of the disc-shaped rigid base without pressing it.

Further, as another fixing method of the recording sheet and the disc-shaped rigid base, a method of adhering the inner peripheral portion and the outer peripheral portion by induction heating using a pressure member (Japanese Patent Application No. 24006).
No. 25), a method of bonding by dielectric heating using a pressing member in the same manner (Japanese Patent Application No. 3-1043), a method of bonding by microwave heating in the same manner (Japanese Patent Application No. 3-21146), and There is a method of bonding by sonic heating (Japanese Patent Application No. 3-49547).

The recording disk having the recording sheet fixed to the disc-shaped rigid base as described above may be subjected to a burnishing treatment for removing surface defects and improving the smoothness of the surface. This burnishing treatment is performed by a method in which a polishing tape is brought into line contact with a recording surface of a recording disk rotating at high speed in a radial direction, or a cylindrical polishing grindstone is rotated at a high speed, and a recording disk rotating at a high speed is rotated in a radial direction. It is carried out by a well-known method for a floppy disk such as a method of making line contact. This burnishing treatment can be performed before fixing the recording sheet to the disc-shaped rigid base, but in general, the burnishing treatment may leave minute circumferential polishing marks on the recording surface. The center of the circumferential polishing mark and the center of the recording track after being fixed are deviated from each other, which is not preferable in recording and reproducing. Therefore, it is preferable to perform the burnishing treatment after fixing the recording sheet to the disc-shaped rigid base.

After that, a defect inspection is performed by actually recording and reproducing a signal on the recording sheet. As a general defect inspection performed on a magnetic recording disk for data,
A method is used in which recording is performed at the highest frequency of the recording signal to be used, the amplitude of each pulse of the reproduction signal is compared with the average signal amplitude of one round of the track, and the pulse position that does not reach the specified level is determined as a defect. ing.

When this recording disk is used as a replaceable medium, it is common to record a servo signal in advance and perform a servo tracking control while inspecting a defect in an area other than the servo signal. Has been done in. As the servo signal, a sector servo system or the like which is well known for magnetic disks and the like is used.

When the recording disk is chucked with the spindle motor shaft of the recording disk drive,
There are cases where the center hole portion of the recording disk is directly attached to the chucking portion on the side of the driving device and used, and there is a case where the center core portion for chucking and determining the center position is previously attached to the center hole portion of the recording disk and used. .. Whichever method is used, it is preferable to make the final chucking form before the defect inspection in terms of track alignment.

However, there were the following problems when manufacturing such a recording disk.

Since the recording track position at the time of performing the defect inspection needs to coincide with the recording track position after the recording disk is completed as a final product, the defect inspection is performed by disc-shaped rigidity with the recording sheet radially extended. It must be done after fixing to the base. However, the recording disk having the number of defective portions larger than the prescribed number in this defect inspection is discarded as a rejected product. Some of the rejected recording disks may be converted to acceptable ones by re-burnishing, but such cases are relatively rare. The members constituting the discarded recording disc include the recording sheet, the disc-shaped rigid base, and the center core in some cases. Even if it is unavoidable to dispose of recording sheets with many defects, the disk-shaped rigid base and the center core account for a high proportion of the component material cost, and their disposal has been a factor of cost increase. Further, their disposal is not preferable from the viewpoint of increasing industrial waste.

It is also conceivable to peel off a recording sheet having many defects from a recording disc that has failed the defect inspection and reuse the disc-shaped rigid base or the center core. Adhesion to the rigid base and center core is extremely strong, it cannot be easily peeled off, and cost increase is inevitable. In addition, it is generally considered that a solvent is used for removing it, but use of the solvent is not preferable from the viewpoint of working environment and safety.

[0027]

In view of the above-mentioned problems of the prior art, the present invention provides a recording disk having a gap between a recording sheet and a disc-shaped rigid base with excellent recording / reproducing characteristics at low cost. It is an object of the present invention to provide a manufacturing method which can be manufactured, has excellent suitability for mass production, and can effectively use resources.

[0028]

A method of manufacturing a recording disk according to the present invention comprises a step of preparing a disc-shaped rigid base having an inner peripheral side annular convex portion and an outer peripheral side annular convex portion, and Forming a recording layer on one surface of a flexible support having a large outer diameter to obtain a recording sheet, and the other surface of the flexible support with the flexible support being radially stretched A temporary fastening step of temporarily fixing the inner peripheral portion and the outer peripheral portion to the inner peripheral side annular convex portion and the outer peripheral side annular convex portion of the disc-shaped rigid base, and the recording layer in the temporarily fixed state. A defect inspection step of performing a defect inspection, and a recording sheet that has passed the defect inspection are subjected to substantially the same stretching condition and relative positional relationship as those of the temporary fixing step. It is characterized by comprising a fixing step of fixing to the convex portion. Is shall.

As a result of the defect inspection, the recording sheet can be easily removed from the disc-shaped rigid base of the recording disc which has failed, and a new recording sheet is similarly temporarily fixed to the disc-shaped rigid base. Then, the defect inspection can be performed.
Therefore, the disc-shaped rigid base can be repeatedly used until a recording disk that is a passing product is obtained.

Further, as a result of the defect inspection, the recording sheet which has been rejected is subjected to a treatment for removing surface defects, and the defect inspection is conducted again, and those which have passed are fixed to the disc-shaped rigid substrate and passed. It can be a recording disc of a product.

The present invention will be described in detail below.

In the method of manufacturing the recording disk of the present invention, the following methods are available for temporarily fixing the recording sheet to the disc-shaped rigid base.

First, the recording sheet is stretched toward the outer peripheral side. A preferable jig for this purpose is an annular jig having substantially the same outer diameter and inner diameter as shown in the sectional view of FIG.
11a, 11b and 12 The material of the annular jig is preferably metal such as duralumin or stainless steel. Further, the coefficient of thermal expansion is preferably smaller than that of the recording sheet. On these surfaces facing each other, one of the annular jigs 11a and 11b has an annular projection 13 whose cross-sectional shape is a convex portion, preferably a wedge shape, and the other annular jig 12 is such that the annular projection 13 is fitted. It has an annular groove 14 and an O-ring 15 located on the inner peripheral side. The O-ring 15 is for ensuring that the annular jigs 11a, 11b, 12 fix the recording sheet, and is preferably made of an elastic body such as synthetic rubber. By sandwiching the outer peripheral portion of the recording sheet 2 with these annular jigs 11a, 11b, 12 and engaging the annular projection 13 and the annular groove 14, the recording sheet 2 is radially extended in the plane radial direction,
Further, it is held in the stretched state by being crimped to the O-ring 15. FIG. 2 shows a state in which the recording sheet 2 is stretched and held by the annular jigs 11a, 11b and 12.

As shown in FIG. 3, while the recording sheet 2 is stretched and held by the annular jigs 11a, 11b and 12, the disc-shaped rigid base 1 is held.
Press on. At this time, the annular pressing jigs 16a, 16b, 1
The recording sheet 2 is pressed against the inner peripheral side annular convex portion 6 and the outer peripheral side annular convex portion 7 of the disc-shaped rigid base 1 by using 9,20. The pressing jigs 16a and 16b have outer peripheral side annular convex portions 18a and 18b at positions corresponding to the outer peripheral side annular convex portion 7 of the disc-shaped rigid base 1. To press the outer peripheral side annular convex portions 18a, 18b of the pressing jigs 16a, 16b against the outer peripheral side annular convex portion 7 of the disc-shaped rigid base 1, a pressing jig is used.
It suffices to tighten the annular jig fixing bolts 21 and nuts 22 provided at several locations on the outer peripheral portions of 16a and 16b. This allows
Disc-shaped rigid base 1, recording sheet 2, annular jigs 11a, 11b, 1
2. The pressing jigs 16a and 16b are connected as a unit.
Further, the pressing jigs 19, 20 have inner peripheral side annular convex portions 17a, 17b at positions corresponding to the inner peripheral side annular convex portion 6 of the disc-shaped rigid base 1. During the pressing process, the slack in tension is further removed. In addition, a desired tension can be applied to the recording sheet by adjusting the height of the annular convex portion on the pressing jig side. The pressing jig 19 is rotatable, and the pressing jig 20 can be coupled to the spindle motor shaft to transmit the rotational force to the recording disk and the jig.

The tension can be easily measured by the penetration stiffness. Penetration stiffness is the force received in the unit of g / mm when the tip of a needle-shaped probe (r = 3.2 mm sphere) is pushed vertically into the recording sheet 2, and the attachment degree (tension) of the sheet is indicated. It can be easily quantified. According to the knowledge obtained so far, when the recording sheet 2 is a magnetic sheet, the measured value of the penetration stiffness and the problem between the head and the medium are correlated, and in particular, the output level shows that the penetration stiffness is in a certain range. It is known that the higher it is, the higher the penetration stiffness is, and the output is saturated when the penetration stiffness exceeds a certain range, and the output is sometimes reduced when the penetration stiffness is increased. From the experimental results of the present inventor, a desirable value of penetration stiffness is 30 to 300 g / mm, more preferably
It has been found to be in the range of 100-200 g / mm. Further, it is preferable that the variation of the penetration stiffness is within 10% in the circumferential direction.
The variation of the penetration stiffness in the radial direction is generally substantially constant except near the center and near the outer peripheral portion.

As described above, the burnishing process is carried out as necessary with the recording sheet 2 temporarily fixed to the disc-shaped rigid base 1.

Further, a defect inspection is carried out in the temporarily fixed state. There are various methods for defect inspection, but as a general method, a signal of the highest frequency used by the recording disk is recorded on one track and the peak value of the reproduced signal is used as the average signal amplitude of one track. There is a method of detecting a missing pulse by comparing with. Also, a retry process can be performed when a defect is detected.

As for the recording disk in the temporarily fixed state which has passed the result of the defect inspection, the relationship between the center positions of the recording sheet 2 and the disc-shaped rigid base 1 at the time of the defect inspection is not changed,
While the radial tension is applied to the recording sheet 2, the inner peripheral portion and the outer peripheral portion of the surface of the recording sheet 2 on the side opposite to the recording surface of the flexible support 4 are formed on the inner peripheral side of the disc-shaped rigid base 1. The protrusion 6 and the outer peripheral annular protrusion 7 are fixed.

The deviation between the track position at the time of defect inspection and the track position of the product after fixing is preferably 10 × with respect to the track pitch Tp when servo tracking is performed.
Tp or less, more preferably 5 × Tp or less, and further preferably Tp or less. When servo tracking is not performed, it is preferably 0.5 x Tp or less, more preferably 0.2 x Tp or less, still more preferably 0.1 x Tp or less. Generally, when servo tracking is not performed, the shift amount becomes the off-track amount as it is, and thus more strict control is required.

The fixing means in the fixing step is not particularly limited, but a conventional adhesive having tackiness and capable of achieving adhesion only by being applied to the adhesive surface can be temporarily fixed. Since it is not suitable, it cannot be applied prior to temporary fastening and its use is not preferred.

Therefore, for the fixation, an appropriate material is selected as the material of the disc-shaped rigid base 1 and the recording sheet 2, or, if necessary, an adhesive that exhibits adhesiveness by applying high-frequency energy is applied to the adhesion location. Give it in advance,
It is preferable to achieve this by applying high-frequency energy to the inner peripheral annular projection 6 and the outer peripheral annular projection 7.
As means for applying energy that can be adopted in the present invention, specifically, a method of adhering by induction heating (Japanese Patent Application No. 2-400625) and a method of adhering by dielectric heating (Japanese Patent Application No. 3-1043). ), A method of bonding by microwave heating (Japanese Patent Application No. 3-21146), a method of bonding by ultrasonic heating (Japanese Patent Application No. 3-49547), and the like. When these methods are used, a pressing jig is required, and this can also be used as the pressing jigs 16a, 16b, 19, 20.
By doing this, it is not necessary to apply adhesive after temporary fixing, and the track position during defect inspection and the track position during actual use can be matched, avoiding defect troubles in the market. It becomes possible to do.

As a result of the defect inspection, the recording disk in the temporarily fixed state, which has failed, may be passed by performing the above-mentioned burnishing treatment while maintaining the temporarily fixed state. This is relatively common when the cause of the defect is caused by adhesive dust or relatively light protrusions. However, it is desirable that the re-burnishing is performed under a slightly weaker condition than the initial burnishing condition so that the smoothness of the surface is not significantly changed. Further, as a characteristic of the recording medium, when the rate of passing the pass by reburnishing is not high, it is better to omit this reburnishing step.

For the recording disk in the temporarily fixed state, which failed the defect inspection after the burnishing again, remove the recording sheet 2 from the disc-shaped rigid base 1 and replace it with a new recording sheet. The disk-shaped rigid base 1 taken out is temporarily fixed in the stretched state using the jigs. Then, the burnishing process and the defect inspection are performed according to the procedure described above. In this way, it is possible to reuse the rejected disc-shaped rigid base 1 without wasting it.

Although the above is an example of the case where the center core is not attached, depending on the system, it is possible to perform temporary fixing and defect inspection of the recording sheet to which the center core is attached.

Further, in the case of the exchangeable medium, the servo signal may be recorded after the burnishing in the temporarily fixed state, and then the defect inspection may be performed.

Thus, after fixing the recording sheet 2 on the disc-shaped rigid base 1, the annular jigs 11 and 12 are removed, and the unnecessary recording sheet 2 protruding from the disc-shaped rigid base 1 is cut and removed. A desired recording disk 10 can be obtained.

As described above, the recording sheet is temporarily stretched on the disc-shaped rigid base in a radially stretched state, and a defect inspection is performed. The manufacturing method of the present invention, which comprises fixing in a positional relationship, does not waste the disc-shaped rigid base, and brings about a significant improvement in manufacturing cost, and at the same time, a significant improvement in effective use of resources and reduction of industrial waste. It is a thing.

The pair of annular projection 13 and annular groove 14 described above are used.
It is possible to use various jigs instead of the annular jigs 11a, 11b, 12 having the one O-ring 15. For example,
The O-ring 15 can be provided not only on the inner peripheral side of the annular projection 13 and the annular groove 14 but also on the outer peripheral side thereof.

The manufacturing method described above is an example in which the recording sheet 2 manufactured in advance is temporarily fixed in a stretched state by the annular jigs 11a, 11b, 12; however, the recording layer 3 on the flexible support 4 is fixed.
Can be formed after the flexible support 4 is temporarily fixed to the annular jig. At this time, the recording layer 3 can be formed by a method such as sputtering, vacuum deposition, spin coating, or plating. The amount of decrease in the tension generated during film formation can be readjusted when the pressing jigs 16a, 16b, 19, 20 are pressed.

In order to prevent long-term storage after completion of the recording disk and reduction of tension in a high temperature and high humidity environment, the recording sheet is temporarily fixed in a stretched state by the annular jigs 11a, 11b, 12 and then heat treated, It is also preferable in terms of quality improvement to readjust the decrease in tension caused thereby by pressing the pressing jigs 16a, 16b, 19, 20.

Other materials relevant to the present invention will be described below.

A typical recording disk is a magnetic disk having a magnetic layer as a recording layer, but the present invention is not limited to the magnetic disk, and various types such as a phase change type optical recording medium and a magneto-optical recording medium can be used. It can be used for manufacturing various recording disks.

As the disc-shaped rigid base, aluminum,
A metal such as an aluminum alloy, glass, a synthetic resin, a resin containing a filler, a combination thereof, or the like can be used.

The disc-shaped rigid base made of synthetic resin is generally inexpensive because it can be manufactured in large quantities by injection molding.

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 disc-shaped rigid base, metal oxides such as TiO ₂ and SiO ₂ and B are used.
5 to 50% by weight of aSO ₄ , glass fiber or the like may be mixed.

The recording sheet is made of a material suitable for the purpose 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.

As the flexible support of the recording sheet, a plastic film such as polyethylene terephthalate (PET) is generally used, and a biaxially oriented polyethylene terephthalate film is particularly preferable, but a polyimide (P
I), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS) and the like can also be used. 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 of the recording sheet 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, or a plating method. It can be formed by using

If the disc-shaped rigid base or the flexible support of the recording sheet is made of a hard thermoplastic or is compatible with each other, it is welded by laser heating or the like without an adhesive. It is possible. However, even in such a case, it is preferable to bond via an adhesive in order to ensure reliable bonding.
Further, the flexible support of the disc-shaped rigid base or recording sheet to be adhered is polyethylene terephthalate (PET),
Polyimide (PI), Polyetherimide (PEI),
If it is composed of polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), aramid, polyolefin (PO), polyacetal (POM), thermosetting plastic, etc., welding is difficult and it is necessary to use an adhesive. Is.

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

As the base polymer of the hot melt adhesive, rubbers such as copolymer polyester, polystyrene butadiene copolymer, acrylonitrile butadiene copolymer, polystyrene isoprene copolymer, ethylene butylene copolymer, polyisobutylene, polybutadiene and butyl rubber are used. 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 tackifiers to be added to these base polymers include natural resins such as rosin, hydrogenated rosin, and rosin esters 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 necessary, the hot-melt adhesive may be mixed with additives such as a filler, an antiaging agent and an ultraviolet protective agent to improve heat resistance and weather resistance.

The blending ratio of these is 100 to 600 parts by weight of tackifier and 0 part of softening agent to 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 is preferably 140 ° C or lower and 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 adhesive portion of the disc-shaped rigid base, and an 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.

[0069]

【Example】

Example 1 As a recording sheet 2, a coercive force of 1500 was formed on a flexible support 4 made of polyethylene terephthalate having a thickness of 32 μm.
Oersted, 0.5 μm thick metal magnetic material for recording layer 3
What was applied as was prepared.

The disc-shaped rigid base 1 was produced by injection molding using a material in which 40% of glass fiber and an inorganic filler were contained in polyetherimide. Its shape is as shown in FIG. 6, each outer diameter r ₁ and the inner diameter r ₂ is 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 Both were set to 1 mm. The thickness d of the disc-shaped rigid base 1 is 2 mm, and the depth t of the annular recess 8 is 0.2 m.
It was m.

As shown in FIGS. 1 and 2, the recording sheet 2 is provided with three annular jigs 11a having an outer diameter of 140 mm and an inner diameter of 100 mm.
The recording layer 3 was sandwiched between 11b and 12 so as to face outward, and stretched and held with a predetermined tension. These 3 ring jigs
11a and 12 and 11b and 12 face each other,
The annular jigs 11a and 11b each have an annular projection 13 having a wedge-shaped cross section, and the annular jig 12 has an annular groove 14 that fits into the annular projection 13 and an O-ring 15 located on the inner peripheral side thereof. Have
The shapes of the annular projection 13 and the annular groove 14 are such that the penetration stiffness, which will be described later, as an alternative property of tension is 15 on the circumference of a radius of 30 mm when the recording sheet 2 is stretched and held.
It was set to 0 g / mm.

Recording sheet 2 thus obtained in a stretched state
Is pressed against the disc-shaped rigid base 1 by using the annular pressing jigs 16a and 16b, the rotationally movable pressing jig 19 and the pressing jig 20 which can be coupled to the spindle motor as shown in FIG. The sheet 2 was temporarily fixed to the disc-shaped rigid base 1.

The recording disk in this state was rotated at 1500 rpm and subjected to tape burnishing treatment using a # 5000 polishing tape to remove minute defects on the recording surface.

Next, a defect inspection was carried out in the temporarily fixed state as follows. First, the temporarily fixed recording disk was rotated at 3600 rpm to record a 2.5 MHz rectangular wave signal. The head slider used is a Whitney type flexure with a load load of 9.5 g equipped with a grooved spherical slider, and an MIG head core embedded therein. The track pitch was 32 μm and the track width was 25 μm. 1/2 of the average signal amplitude of the reproduced signal for one track
The peak value of the reproduced signal that is less than 45% of the
More than 64 recording discs were judged as rejected.

As for the acceptable products, the inner circumferential side annular convex portion 6 of the disc-shaped rigid base 1 is preliminarily changed without changing the central positions of the recording sheet 2 and the disc-shaped rigid base 1 and the tensions of the recording sheet 2 in the temporarily fixed state. Then, the recording sheet 2 and the disc-shaped rigid base 1 were fixed by ultrasonic welding via a hot melt adhesive (Chemit solution K-1089 manufactured by Toray) applied to the adhesive surface of the outer peripheral annular projection 7.

The rejected product was subjected to the burnishing treatment again in the temporarily fixed state. At this time, the pressure with which the polishing tape was pressed was set to 1/2 of the initial burnishing time. After that, the defect inspection was performed again, and for the acceptable product, the recording sheet 2 and the disc-shaped rigid base 1 were fixed by ultrasonic welding as described above.

For the temporarily fixed recording discs that failed the defect inspection again, the recording sheet 2 is removed from the disc-shaped rigid base 1, and a new recording sheet 2 is attached to the disc-shaped rigid base 1 by the above-mentioned jig. It was temporarily fixed and burnished as described above. Then, defect inspection was performed under the above-mentioned conditions. As a result, for those that passed, the recording sheet 2 and the disc-shaped rigid base 1 were fixed by ultrasonic welding as described above, and for those that failed, a new recording sheet 2 was replaced until they passed. Was repeated.

A recording disk 10 was finally obtained by cutting an extra portion of the recording sheet 2 of the sample obtained as described above. The evaluation results are shown in Table 1.

[0079]

[Table 1]

The measurement conditions are the same as those for the defect inspection. The modulation indicates the fluctuation of the P-P value of the reproduction signal amplitude around the track, and is defined by {(maximum output-minimum output) / (maximum output + minimum output)} × 100%. As the average signal amplitude, the average value of the P-P values of the reproduced signal amplitude of one track of the track was shown as a relative value, with the first pass product being 0 dB.

[0081]

According to the method of manufacturing a recording disk of the present invention, since the defect inspection is performed with the recording sheet and the disc-shaped rigid base temporarily fixed, the rejected product is replaced with a new recording sheet. The disk-shaped rigid base that occupies a relatively large proportion as a member of can be reused without wasting it, not only can the manufacturing cost be reduced, but also resources can be reused and industrial waste can be reduced. it can. Further, in terms of quality, the recording track used by the user and the track position at the time of defect inspection can be matched, so that it is possible to manufacture a highly reliable recording disk having no defect quality problem.

In some cases, by reburnishing a temporarily fixed recording disk that has failed the first defect inspection, the recording sheet can be converted into a passing product without replacing the recording sheet. This re-burnishing process can further reduce the manufacturing cost and make effective use of resources.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an annular jig used in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a flexible support stretched and held by the annular jig of FIG. 1 in one embodiment of the present invention.

FIG. 3 is a cross-sectional view showing these members and a pressing member when temporarily fixing the recording sheet stretched and held by the annular jig of FIG. 1 to a disc-shaped rigid base in one embodiment of the present invention.

FIG. 4 is a sectional view showing an example of a recording sheet used in the present invention.

FIG. 5 is a sectional view showing an example of a recording disk manufactured according to the present invention.

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

[Explanation of symbols]

 1 Disc-shaped rigid base 2 Recording sheet 3 Recording layer 4 Flexible support 5 Gap 6 Inner peripheral side annular convex portion 7 Outer peripheral side annular convex portion 8 Annular recess 9 hole 10 Recording disk 11a Circular jig 11b Circular jig 12 Circular Jig 13 Annular protrusion 14 Annular groove 15 O-ring 16a Pressing jig 16b Pressing jig 17a Inner peripheral annular convex part 17b Inner peripheral annular convex part 18 Outer peripheral annular convex part 19 Pressing jig 20 Pressing jig 21 Annular Jig fixing bolt 22 Annular jig fixing nut

Claims (2)

[Claims] 1. A step of preparing a disc-shaped rigid base having an inner peripheral side annular convex portion and an outer peripheral side annular convex portion, and one surface of a flexible support having an outer diameter larger than that of the disc-shaped rigid base. A step of forming a recording layer to obtain a recording sheet, and in a state where the flexible support is radially stretched, the inner peripheral portion and the outer peripheral portion of the other surface of the flexible support are formed of the disc-shaped rigid base. Temporary fixing step of temporarily fixing to the inner peripheral annular convex portion and the outer peripheral annular convex portion, a defect inspection step of performing a defect inspection of the recording layer in the temporarily fixed state, and pass the defect inspection And a fixing step of fixing the recording sheet to the inner peripheral side annular convex portion and the outer peripheral side annular convex portion of the disc-shaped rigid base under substantially the same stretching condition and relative positional relationship as the temporary fixing step. Recording disk manufacturing method. 2. The high-frequency energy is applied to the inner peripheral side annular convex portion and the outer peripheral side annular convex portion of the disc-shaped rigid base while holding the flexible support temporarily fixed. The fixing is performed according to claim 1.
The manufacturing method described.