JPH07210926A - Composite disk - Google Patents

Abstract

PURPOSE:To obtain a stable traveling characteristic in spite of contact traveling by forming a protective layer for a magnetic layer of a UV curing resin contg. a solid lubricant and liquid lubricant or either one thereof. CONSTITUTION:The optical disk 15 is obtd. by forming signal pits 2 on a substrate 1 made of a transparent polycarbonate resin, forming an Al film as an optical recording layer 3 thereon and forming the protective layer 4 for the optical recording layer by curing a UV curing resin thereon. The magnetic layer 5 is formed on the disk 15 by curing and flattening a magnetic coating material film. A UV curing monomer mixture essentially consisting of a urethane acrylate added with 7wt.% a fluorine denatured silicone resin which is the solid lubricant in a dispersed state without completely dissolving this resin is applied on the layer 5 and thereafter, the cured magnetic protective layer 6 is formed. The surface of the protective layer 6 is ground, by which the composite disk 10 is formed. As a result, an effect of decreasing and grinding a contact area is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite disc obtained by forming an optical disc having an optical recording layer on which a magnetic layer capable of writing / reading a small amount of data by a magnetic head is formed. The present invention relates to a composite disk suitable for forming an optimum magnetic layer protective layer on a layer and allowing good contact running of a magnetic head.

[0002]

2. Description of the Related Art A read-only optical disc for reading out an information signal recorded on an optical recording layer formed on a transparent substrate by using laser light can reproduce a large amount of the same information in a short time. As a result, it is now widely used. This read-only optical disc is classified into a CD, a CD-ROM, a CD-V, a CD-I, etc. depending on the recorded information content.

With the advent of these various types of read-only optical discs, their usage forms have become diversified. Further, an attempt has been made to facilitate management of the read-only optical disk by providing a recording area on the read-only optical disk in which a small amount of information can be added and recording management information therein. For example, a play-only optical disc for games (hereinafter,
In the case of (game optical disc), when the game is interrupted in the middle and restarted again, the scene number of the game at the time of interruption and the score of the game so far can be started so that it can be started from the interrupted scene. Although the game management information can be recorded in the optical disk player, if the game optical disk is taken to another place and the game is restarted by another optical disk player there, the game management information is stored in the optical disk player. Since it was recorded in, and was not recorded in the game optical disk, it was not possible to resume from the scene where it was interrupted.

Therefore, in order to solve such a drawback, for example, JP-A-62-75956 and JP-A-1 are used.
As disclosed in Japanese Patent Laid-Open No. 138642 or Japanese Patent Laid-Open No. 4-337546, an area of a magnetic layer in which a small amount of information can be written / read (hereinafter also referred to as recording / reproducing) on an optical disk by a magnetic recording method. It has been proposed to provide a composite disc.

A conventional technique will be described below with reference to the accompanying drawings. FIG. 1 is a partial cross-sectional view showing the structure of a general composite disc. In FIG. 1, 1 is a substrate, 2 is a signal pit, 3 is an optical recording layer, 4 is a protective layer for an optical recording layer,
Reference numeral 5 is a magnetic layer, 6 is a magnetic layer protective layer, 10 is a composite disc, and 15 is an optical disc.

A signal pit 2 corresponding to information is formed on one surface of a substrate 1 made of a transparent disc-shaped polycarbonate resin.
Is formed by the injection molding method, and the optical recording layer 3 made of aluminum is formed thereon. The optical recording layer 3 is for reading the shape of the signal pit 2 by allowing laser light to enter from the side of the substrate on which the signal pit 2 is not formed and reflected by the optical recording layer 3. The optical recording layer protective layer 4 made of an ultraviolet curable resin is formed on the optical recording layer 3 to form the optical disc 15. Further, a magnetic layer 5 having a predetermined shape is formed on the protective layer 4 for the optical recording layer to write / read a small amount of rewritable information by a magnetic recording method. In order to prevent the magnetic layer 5 from being damaged by sliding of a magnetic head (not shown), a magnetic layer protective layer 6 made of resin and, if necessary, a lubricating layer (not shown) are sequentially formed on the magnetic layer 5, A composite disk 10 is constructed. Magnetic recording / reproduction on the magnetic layer 5 is performed by a magnetic head (not shown).

[0007]

By the way, as compared with the conventional magnetic recording medium, the optical disk has a low disk rotation speed and large surface wobbling. Therefore, a magnetic layer is provided on the optical disc to form a composite disc, and the management information is magnetically recorded / recorded on the magnetic layer.
When reproducing, in order to stably run the magnetic head on the composite disk, it is necessary to adopt a contact recording method in which the magnetic head is brought into contact with the composite disk while applying a predetermined load.

However, in order to obtain a stable magnetic recording / reproducing output, it is necessary to improve the followability of the magnetic head to the surface wobbling of the composite disk. Further, it is necessary to avoid damage to the optical recording layer caused by pressing the magnetic head against the composite disk while applying a predetermined load. Further, in order to perform magnetic recording / reproduction with high output and low noise, it is necessary to narrow the spacing between the magnetic head and the magnetic layer. Further, it is necessary to avoid damage caused to the magnetic layer and the magnetic head due to the contact traveling. Furthermore, it is necessary to consider simplification of the manufacturing process of the composite disk.

In consideration of these points, the applicant of the present invention forms a magnetic layer having a predetermined shape on a conventional optical disc, and protects the magnetic layer made of an ultraviolet curable resin on the magnetic layer. Various composite discs in which a layer and a lubricating layer were sequentially formed were manufactured, and the durability of the stable drive of the composite disc when the magnetic head was made to travel by the magnetic head contact method was studied for these composite discs. .

According to this, when the magnetic layer protective layer and the magnetic head are brought into contact with each other (the lubricating layer is interposed) and contact travel is performed, in order to obtain stable running characteristics, the magnetic head is applied to the magnetic head. It is necessary to increase the contact load sufficiently,
Therefore, although sufficient magnetic recording and reproducing characteristics were obtained at the beginning of running the magnetic head, continuous use
Friction between the magnetic layer protective layer and the magnetic head causes stick-slip of the magnetic head, which makes stable running of the magnetic head impossible, or the magnetic layer protective layer is worn out and then scratches occur in the magnetic layer. Found that the magnetic head would crash.

Therefore, the present invention has been made by paying attention to the above points, and in a composite disk, even if the composite head is in contact travel with a magnetic head to which a predetermined contact load is applied,
An object of the present invention is to provide a composite disk having a magnetic layer protective layer having stable running characteristics so that a reliable magnetic head running characteristics can be formed.

[0012]

A composite disk of the present invention comprises a disk-shaped transparent substrate, an optical recording layer on which optical information is recorded, a protective layer for the optical recording layer, and a magnetic layer having a predetermined shape. When,
In the composite disc in which the magnetic layer protective layer is sequentially laminated, the magnetic layer protective layer is formed of an ultraviolet curable resin containing a solid lubricant and a liquid lubricant or any one of them. It achieves the purpose.

Further, the composite disk of the present invention comprises an optical recording layer on which optical information is to be recorded, a protective layer for the optical recording layer, a magnetic layer having a predetermined shape, and a magnetic layer on a disk-shaped transparent substrate. In a composite disc in which a protective layer is sequentially laminated, the magnetic layer protective layer is formed by an ultraviolet curable resin containing a solid lubricant and / or a liquid lubricant, and inorganic abrasive fine particles. It achieves the above-mentioned object.

[0014]

[Function] In the ultraviolet curable resin constituting the magnetic layer protective layer,
Since the solid lubricant and the liquid lubricant or any one of them are contained, the lubricant dispersed between the magnetic head and the magnetic layer protective layer causes a lubrication action during contact travel of the magnetic head, which causes friction. Since the force is reduced, the change in the surface shape of the magnetic layer protective layer can be suppressed to a small level, and the contact traveling by the magnetic head can be stably maintained.

Since the ultraviolet curable resin constituting the magnetic layer protective layer contains the solid lubricant and / or the liquid lubricant, and the inorganic abrasive fine particles, the contact travel of the magnetic head is The lubricant dispersed between the magnetic head and the magnetic layer protective layer causes a lubricating effect, and the inorganic abrasive fine particles dispersed as protrusions on the surface of the magnetic layer protective layer reduce the effective contact area of the magnetic head. Therefore, since the frictional force is reduced, the change in the surface shape of the magnetic layer protective layer can be suppressed to a small level, the adhesion of the magnetic head can be prevented, and the contact traveling by the magnetic head can be stably maintained.

[0016]

[Example] A composite disk was manufactured, and a magnetic head was made to contact and run, and a sliding test was conducted. Hereinafter, referring to the drawings,
Examples of the present invention will be described. FIG. 1 is a partial cross-sectional view showing the structure of a general composite disc. First, the outline of the configuration of the optical disc 15 will be described. Signal pits 2 are formed on a transparent polycarbonate resin substrate 1 having a diameter of 120 mm by an injection molding method using a stamper. A thickness of 1 is formed on the entire surface of the signal pit 2 by sputtering.
An Al film of 00 nm is formed as the optical recording layer 3. On this optical recording layer 3, a UV-curing resin made of, for example, trimethylpropane triacrylate (TMPTA) is applied by a spin coat method and then cured by UV rays to protect the optical recording layer having a thickness of 7 μm. The layer 4 is formed and the optical disc 15 is obtained.

<Embodiment 1> The optical disk 15 having the above configuration
Then, a magnetic paint mainly containing an ultraviolet curable resin (which will be described later) is applied by a screen printing method (screen).
The emulsion is Tetron type 380 mesh, and the emulsion is applied to a thickness of 12 μm. The inner diameter is 39 mm and the outer diameter is 11 mm.
8 mm doughnut-shaped opening is provided) to form a magnetic paint film having a predetermined shape. This magnetic paint film was cured by ultraviolet irradiation, and then the surface was tape-polished using a polishing tape to be flattened to obtain a magnetic layer 5 having a film thickness of 5 μm (for tape polishing). Will be described later).

An ultraviolet-curable monomer mixture containing urethane acrylate as a main component, to which 7 wt% of a fluorine-modified silicon resin as a solid lubricant, which is not completely dissolved but dispersed, is added on the magnetic layer 5. (This will be described later) was applied by a spin coat method and then cured by ultraviolet rays to form a magnetic layer protective layer 6 having a thickness of 1.5 μm. Further, the surface of the magnetic layer protective layer 6 was polished with a predetermined amount of a polishing tape to obtain a composite disk 10 of Example 1. After the magnetic layer protective layer 6 was formed, its surface roughness was measured by a contact type surface roughness meter (Rank Teller-Hobson Co., Ltd.), and the value of the center line surface roughness Ra was 4
0 nm was obtained.

This composite disk 10 was mounted on a composite disk sliding tester (which will be described later), and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.37, and the coefficient of friction after the sliding test was 0.40. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6. The sliding test conditions were as follows. The contact load of the magnetic head is 3 g and the magnetic head slider is a calcium titanate / ferrite composite slider. The rotation speed of the composite disk 10 is 330.
The sliding position of rpm and the magnetic head was a track of the composite disk 10 having a radius of 40 mm, and a 20,000-pass sliding test was conducted.

Next, the magnetic paint used to form the magnetic layer 5 will be described. The magnetic paint is acrylic acid ester-based trimethylpropane triacrylate (TMP).
TA: manufactured by Nippon Kayaku Co., Ltd., and γ-Fe ₂ as magnetic powder.
CMX-473 which is O ₃ (trade name, Toda Kogyo Co., Ltd.)
Manufactured by Nippon Kayaku Co., Ltd.) and hydroxypivalate neopentylglycol diacrylate monomer (MANDA: Nippon Kayaku Co., Ltd.)
Manufactured by Dalocure-4265 (trade name, as a photo-curing agent).
5% by weight of Merck Japan Co., Ltd. added,
It was prepared by thoroughly mixing with a ball mill and dispersing magnetic powder.

Next, the tape polishing used for the surface polishing of the magnetic layer 5 and the magnetic layer protective layer 6 will be described. First,
The polishing device will be described. FIG. 2 is a perspective view showing a schematic configuration of a tape polishing apparatus for a composite disk. The tape polishing device 30 is roughly composed of a tape feeding section and a disk mounting section. The disk mounting portion (not shown) refers to the composite disk 10 (more precisely, the one on which the magnetic layer 5 is formed on the optical disk 15 or the one on which the magnetic layer protective layer 6 is further formed, but for simplicity, A composite disc) is clamped in place and can be rotated about a center axis of rotation 38 (which is coincident with the center axis of rotation of the composite disc 10).

On the side plate (not shown) of the tape feeding section,
Supply roll 32a, winding roll 32b, roll 33, guide rolls 36a, 36b, capstan roll 34,
Tension rollers 35 are rotatably attached to respective predetermined positions. The tape feed unit is vertically movable, and the vertical direction of the central axis of rotation 38 (that is, the composite axis) so that the roller 33 can scan a predetermined surface of the composite disk 10 in the direction of its rotation axis 39. It is also movable in the radial direction of the disk 10. The cylindrical surface of the roller 33 is parallel to the upper surface of the composite disk 10.

Polishing tape 31 (hereinafter, for simplicity, the tape is
One end of the tape 31) is wound around the supply roll 32a, and the other end is wound around the winding roll 32b. During that time, the tape 31 is fed at a predetermined feed speed. Capstan roller 34, a guide roller 36a for preventing displacement due to running of the tape 31, and a roller 33 for pressing the tape 31 onto the surface of the composite disk 10 with a predetermined pressure.
The guide roller 36b for preventing the deviation of the tape 31 due to running and the tension roller 35 for applying the tension for winding the tape pass through predetermined positions. In FIG. 2, the arrow on the composite disk 10 indicates the direction in which the composite disk 10 is rotated, the arrow along the tape 31 indicates the traveling direction of the tape 31, and the arrow on the roller 33 indicates. , And the moving direction of the tape feeding section (the roller 33 moves in conjunction). Tape 31 is a commercially available polishing tape, and the polishing agent used is WA # 2000.

Next, the tape polishing process will be described. First, the composite disk 10 on which the ultraviolet-cured magnetic paint film is formed is set in the tape polishing apparatus 30, and the tape 31 is set.
Is continuously fed at a constant feeding speed in the tape feeding direction indicated by the arrow in the figure so that the surface to which the alumina particles are adhered is in contact with the surface of the magnetic paint film, while being fed by the roller 33,
First, it is pressed against the outermost peripheral surface of the composite disk 10, and then the roller 33 is scanned in the radial direction of the composite disk 10 at a constant speed. When the tape 31 and the roller 33 reach the innermost peripheral side of the composite disk 10, this time, on the contrary, scanning is performed to the outermost peripheral side. It reaches the outermost peripheral side again, and is set to one scanning cycle. Further, in the composite disk having the magnetic layer protective layer formed thereon, tape polishing of the magnetic layer protective layer is also performed in the same process.

The tape polishing processing conditions were as follows. The rotation speed of the composite disk 10 is 100 rpm.
The roller 33 has a predetermined cylindrical shape made of rubber (or a stainless steel material), and a pressure of 20 psi is applied to the roller 33 to press the tape 31 against the composite disk 10. The tape feed rate was 10 cm / min. The scanning speed of the roller 23 in the radial direction of the optical disk 12a is
The scanning cycle is 15 cm / min, the scanning cycle is 10 times when polishing the magnetic layer, and 3 scanning times when polishing the magnetic layer protective layer.
It was time.

Next, the UV-curable monomer mixture containing urethane acrylate as a main component and used for forming the magnetic layer protective layer 6 will be described. UV curing monomer
The mixture is urethane acrylate UX101H
(Trade name, manufactured by Nippon Kayaku Co., Ltd.), MANDA, and T
Prepared by adding 7 wt% of Darocur-1173 (trade name, manufactured by Merck Japan Co., Ltd.) as a photo-curing agent to a mixture of MPTA and WTA at a weight ratio (wt%) of 5: 3: 2. is there. The viscosity before UV curing was 80 cP.

Next, the outline of the sliding tester for the composite disk and the sliding test will be described. FIG. 3 is a front view showing a schematic configuration of a sliding tester for a composite disk. In FIG. 3, 20
Is a sliding tester, 10 is a composite disk, 21 is a clamp, 22 is a spindle, 23 is a central axis of rotation, 24
Is a magnetic head, 25 is a suspension, 26 is a head fixing part, 27 is a load cell, 28 is an arm.
9 shows a surface plate, respectively.

A motor (not shown) is fixed to a base (not shown) of the sliding tester 20. A spindle 22 is rotatably connected to the rotary shaft of this motor. The rotation center axis 23 of the spindle 22 is in the vertical direction. The composite disk 10 is mounted on the protrusion of the spindle 22 penetrating its center hole, and is fixed to the spindle 22 by the clamp 21.

On the other hand, a surface plate 29 fixed to the base is arranged at a predetermined distance from the spindle 22. The upper surface 29a of the surface plate 29 is configured to be movable in the vertical and horizontal directions (direction toward the rotation center axis 23 of the spindle 22). The load cell 27 is arranged and fixed at a predetermined position on the upper surface 29a of the surface plate 29. One end of the arm 28 is connected to the load cell 27 at a support point inside the load cell 27 so that the arm 28 can be horizontally swung, and the other end of the arm 28 has a head fixing portion. 26 is fixed. At the predetermined position of the head fixing portion 26, the suspension 2
One end of the suspension 5 is fixed, and the magnetic head 24 is attached to the other end of the suspension 25 so as to be arranged on the upper surface of the composite disk 10. The position of the magnetic head 24 on the composite disk 10 is adjusted by moving the surface plate 29 in the horizontal direction. The contact load of the magnetic head 24 is adjusted by the vertical movement of the surface plate 29, and is detected by the load cell 27.

Next, the outline of the sliding test will be described. The composite disk 10 is rotated at a predetermined rotation speed by a spindle 22 connected to a motor (not shown). A predetermined contact load is applied to the magnetic head 24 on the composite disk 10, and a frictional force acts in the rotating direction of the composite disk 10. The magnitude of the frictional force is proportional to the amount of horizontal displacement of the arm 28 and is detected by the load cell 27. The change in frictional force with time is recorded in a recorder (not shown) connected to the output end of the load cell 27.

<Embodiment 2> On the magnetic layer 5, 5 wt% of a fluorine-modified silicon resin, which is a solid lubricant, was dispersed without being completely dissolved, and the average particle diameter was 0.15 μm.
The above-mentioned UV-curable monomer mixture containing 0.5% by weight of alumina fine particles is coated by a spin coat method and then cured by UV rays to form a magnetic layer protective layer 6 having a thickness of 1.5 μm. Further, Example 2 was carried out in the same manner as Example 1 except that the surface of the magnetic layer protective layer 6 was polished with a predetermined amount of polishing tape to form the magnetic layer protective layer 6.
A composite disk 10 of was obtained. The center line surface roughness Ra after forming the magnetic layer protective layer 6 was 30 nm.

This composite disk 10 was mounted on a composite disk sliding tester 20 and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.35, and the coefficient of friction after the sliding test was 0.45. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

Example 3 7 wt% of methylphenylpolysiloxane (KF-54: trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) (viscosity 440 cP), which is a liquid lubricant, was added on the magnetic layer 5. After coating the UV-curable monomer mixture by spin coating, it is cured by UV to form a magnetic layer protective layer 6 having a thickness of 1.5 μm, and the surface of the magnetic layer protective layer 6 is A composite disk 10 of Example 3 was obtained in the same manner as in Example 1 except that the magnetic layer protective layer 6 was formed by polishing using a predetermined amount of polishing tape.
The center line surface roughness Ra after forming the magnetic layer protective layer 6 is 30 n.
It was m.

This composite disk 10 was mounted on a composite disk sliding tester 20 and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.42, and the coefficient of friction after the sliding test was 0.46. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

Example 4 The above UV-curable monomer mixture prepared by adding 5 wt% of fluorine-modified silicon resin and 7 wt% of methylphenylpolysiloxane (viscosity 440 cP) on the magnetic layer 5 was spin-coated. And then cured by ultraviolet rays to form a magnetic layer protective layer 6 having a thickness of 1.5 μm, and further, the surface of the magnetic layer protective layer 6 is polished by a predetermined amount using a polishing tape. , NF-30 (trade name, manufactured by Toray Dow Corning Co., Ltd.), which is dimethylpolysiloxane diluted with n-hexane as a solvent to about 0.25 wt%, is applied by a spin coat method to form a film having a thickness of 10 nm. Example 1 except that a lubricating layer was formed
A composite disc 10 of Example 4 was obtained in the same manner as in. The center line surface roughness Ra after forming the magnetic layer protective layer 6 was 30 nm.

This composite disk 10 was mounted on a composite disk sliding tester, and a sliding test using a magnetic head was performed. The coefficient of friction at the beginning of sliding was 0.44, and the coefficient of friction after the sliding test was 0.44. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

<Embodiment 5> On the same optical disk 15 as that used in Embodiment 1, a chromium layer having a thickness of 50 nm, which is not shown, and a cobalt layer having a thickness of 200 nm, which is a magnetic layer 5, are formed on the optical disk 15 by sputtering. A chromium-tantalum alloy magnetic layer is sequentially formed, and 5 wt% of fluorine-modified silicon resin and a viscosity of 100 c are formed on the magnetic layer 5.
A UV-curable monomer mixture containing 5 wt% of a mixture of methylphenylpolysiloxane of P and methylphenylpolysiloxane having a viscosity of 660 cP in a weight ratio of 1: 4 was applied by spin coating and then cured by ultraviolet light. A magnetic layer protective layer 6 having a thickness of 1.5 μm was formed, and the surface of the magnetic layer protective layer 6 was polished with a predetermined amount of polishing tape to obtain a composite disk 10 of Example 5. .
The center line surface roughness Ra after forming the magnetic layer protective layer 6 is 30 n.
It was m.

This composite disk 10 was mounted on a composite disk sliding tester, and a sliding test using a magnetic head was performed. The coefficient of friction at the beginning of sliding was 0.45, and the coefficient of friction after the sliding test was 0.48. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

Example 6 On the magnetic layer 5, 3 wt% of fluorine-modified silicon resin, 5 wt% of dimethylpolysiloxane WF-30 (viscosity 140 cP), and 0% of alumina fine particles having an average particle diameter of 0.15 μm were used. A UV-curable monomer mixture added by 0.5 wt% was applied by a spin coat method, and then cured by UV to have a thickness of 1.5.
A composite disk of Example 6 was prepared in the same manner as in Example 5 except that the magnetic layer protective layer 6 having a thickness of μm was formed and the surface of the magnetic layer protective layer 6 was polished by using a predetermined amount of polishing tape. 1
I got 0. Center line surface roughness Ra after formation of the magnetic layer protective layer 6
Was 35 nm.

This composite disk 10 was mounted on a composite disk sliding tester, and a sliding test using a magnetic head was performed. The coefficient of friction at the beginning of sliding was 0.27, and the coefficient of friction after the sliding test was 0.37. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

Example 7 On the magnetic layer 5, methylphenylpolysiloxane KF-54 (with a viscosity of 440 c) was used.
P) was added by 7 wt% and titania fine particles having an average particle diameter of 0.2 μm was added by 0.2 wt%, and the mixture was applied by a spin coat method and then cured by ultraviolet rays to have a thickness of 1.5 μm. 7. The composite disk 10 of Example 7 was prepared in the same manner as in Example 5 except that the magnetic layer protective layer 6 was formed, and the surface of the magnetic layer protective layer 6 was polished with a predetermined amount of polishing tape. Got The center line surface roughness Ra after forming the magnetic layer protective layer 6 was 30 nm.

This composite disk 10 was mounted on a composite disk sliding tester, and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.40, and the coefficient of friction after the sliding test was 0.55. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

<Example 8> On the magnetic layer 5, 5 wt% of a fluorine-modified silicon resin, 5 wt% of a mixture of methylphenylpolysiloxane having a viscosity of 100 cP and methylphenylpolysiloxane having a viscosity of 660 cP in a weight ratio of 5 wt%, and an average of A UV-curable monomer mixture containing 0.2% by weight of alumina fine particles having a particle diameter of 0.15 μm was applied by a spin coat method and then cured by UV rays to a thickness of 1.
A protective layer 6 for a magnetic layer having a thickness of 5 μm is formed, and the surface of the magnetic layer protective layer 6 is polished with a predetermined amount of a polishing tape, and then, with approximately 0.075 wt% of perfluoropolyether. AM2001 (trade name, manufactured by Montecatini)
Fluorinate F, a perfluoroalkyl containing
C-77 (trade name, manufactured by Sumitomo 3M Ltd.) was dipped in a solution and pulled up at a pulling rate of 4 mm / sec to obtain a film thickness of 6
A composite disk 10 of Example 8 was obtained in the same manner as in Example 5 except that a lubricating layer (not shown) having a thickness of 10 nm was formed. The center line surface roughness Ra after forming the magnetic layer protective layer 6 was 30 nm.

This composite disk 10 was mounted on a composite disk sliding tester, and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.42, and the coefficient of friction after the sliding test was 0.42. The running state of the magnetic head at the end of the sliding test was stable running. After the sliding test, no sliding scratch was generated on the magnetic layer protective layer 6.

Comparative Example 1 An ultraviolet curable monomer mixture was applied on the magnetic layer 5 by a spin coat method, and then,
It is cured by ultraviolet rays to form a magnetic layer protective layer 6 having a thickness of 1.5 μm, and the surface of the magnetic layer protective layer 6 is polished by a predetermined amount of a polishing tape to protect the magnetic layer protective layer. 6
A composite disk 10 of Comparative Example 1 was obtained in the same manner as in Example 1 except that the above was formed. The center line surface roughness Ra after forming the magnetic layer protective layer 6 was 30 nm.

This composite disk 10 was mounted on a composite disk sliding tester 20 and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.44, and the coefficient of friction after the sliding test was 1.20. At the end of the sliding test, the magnetic head had a head crash, and the magnetic layer protective layer 6 had many sliding scratches.

<Comparative Example 2> On the magnetic layer 5, an average grain size of 0.
An ultraviolet-curing monomer mixture containing 0.5 wt% of alumina fine particles of 15 μm dispersed therein was applied by a spin coat method and then cured by ultraviolet rays to form a protective layer 6 for a magnetic layer having a thickness of 1.5 μm. The composite of Comparative Example 2 was formed in the same manner as in Example 5 except that the magnetic layer protective layer 6 was formed and the surface of the magnetic layer protective layer 6 was polished by a predetermined amount using a polishing tape to form the magnetic layer protective layer 6. The disk 10 was obtained. The centerline surface roughness Ra after forming the magnetic layer protective layer 6 was 45 nm.

This composite disk 10 was mounted on a composite disk sliding tester 20 and a sliding test was conducted using a magnetic head. The coefficient of friction at the beginning of sliding was 0.35, and the coefficient of friction after the sliding test was 1.05. At the end of the sliding test, the magnetic head had a head crash, and the magnetic layer protective layer 6 had many sliding scratches.

The structures of the magnetic layer protective layer and the results of the sliding test for Examples 1 to 8 and Comparative Examples 1 and 2 are summarized in Table 1 below.

[0050]

[Table 1]

In Table 1, the number in the parentheses in the column of the structure of the magnetic layer protective layer shows that added to the UV-curable monomer mixture. In each of the examples, the values of the friction coefficient were stable until the end of the sliding test, and both the composite disk (magnetic layer protective layer) and the magnetic head were found to have sliding scratches and stains due to abrasion powder. I couldn't do it.
Particularly when the lubricating layer is formed as in Examples 4 and 8, particularly good results are obtained. Also, magnetic recording / reproducing characteristics were measured before and after the sliding test, but there was no change in reproducing output and C / N value. On the other hand, in each of the comparative examples, the value of the coefficient of friction was good at the beginning of the sliding test, but the value of the coefficient of friction increased after sliding,
Large sliding scratches were generated on the composite disk (magnetic layer protective layer), and a large amount of abrasion powder was observed on the magnetic head.
Further, the magnetic head causes stick-slip, and the running of the magnetic head becomes unstable, and it is impossible to measure the magnetic recording / reproducing characteristics after sliding.

The UV curable monomer mixture
The reason for forming the magnetic layer protective layer is as follows. Since the constituent material of the optical disk is mainly resin, when forming the magnetic layer protective layer on this, heating or high pressure cannot be applied. Therefore, as the main material of the magnetic layer protective layer, a photo-curable resin that can be easily formed by various printing methods such as spin coating, offset printing and screen printing is most suitable, and in particular, a thin film should be formed. In consideration of the above, it is desirable to use the spin coat method, and it is necessary that the viscosity of the UV-curable monomer mixture is in the range of 20 to 500 cP suitable for it.
In particular, the ultraviolet curable material having an acryloyl group in the monomer molecule has a wide variety of types such as the skeleton monomer molecular structure, the number of functional groups, and the viscosity, and after curing depending on their selection and the concentration of the curing agent added. Since the film strength and thermal properties are almost determined, it is possible to obtain the optimum composition of the magnetic layer protective layer.

A film that easily undergoes plastic deformation and is easily worn or a film that does not cause strength reduction or melting due to heat generation during contact traveling with a magnetic head having a predetermined applied load is preferable. In order to prevent it, the mechanical strength and thermal properties of the film must be specified within a predetermined range, assuming that a mechanical surface treatment is also performed. , Because the optimum one can be selected.

Although the fluorine-modified silicon resin as the solid lubricant and the methylphenylpolysiloxane and the dimethylpolysiloxane as the liquid lubricant have been described above as the solid lubricant in the magnetic layer protective layer, the present invention is not limited to these and saturated. Hydrocarbons, unsaturated hydrocarbons, fatty acids and their esters, compounds such as amines, fluorine-substituted fatty acids and their compounds such as amines, and organic silicon compounds such as organic polysiloxanes can be used. It is preferable because it can be widely used up to solids. The liquid lubricant contained in the magnetic layer protective layer preferably has a content of 1 wt% or more in order to perform the function of the lubricant, but if the content of the liquid lubricant increases, aggregation of the lubricant may occur. The strength of the protective layer itself is reduced. In general, the liquid lubricant easily disperses and dissolves in the ultraviolet curable resin, so that it can be contained up to 10 wt%.

Even when a solid lubricant which is in a solid state at room temperature is used, if the content is increased, the effect as a lubricant functions, but in addition, it is appropriately dissolved in an ultraviolet curable resin as a base material. If a lubricant having parameters is selected from the above-mentioned materials, it can be aggregated or microcrystallized in the magnetic layer protective layer, which is also effective in reducing the contact area with the magnetic head. . Further, aiming at the same effect, solid lubricating fine particles may be contained in the magnetic layer protective layer, and carbon, graphite, molybdenum disulfide, melamine and the like are effective, and the particle diameter thereof is the inorganic polishing fine particles described later. Similarly, those within a predetermined range are selected. However, if the content is too large, the surface roughness after film formation becomes large, and it becomes difficult to control the surface roughness even if tape polishing is performed. The solid lubricant is preferably 1 wt% or more and 10 wt% or less, and the solid lubricating fine particles are 0.1 wt% or more and 3 wt% or less.
Wt% or less is preferable. Such solid lubricants and fine particles can be made to have the effect as polishing fine particles by aggregating or finely crystallizing the solid lubricant and fine particles within the operating temperature range.

Although alumina fine particles (Al ₂ O ₃ ) and titania fine particles (TiO ₂ ) have been described as the inorganic polishing fine particles, the present invention is not limited to these.
Metal oxides such as silica (SiO ₂ ) are preferable, and metal sulfides, carbides, and nitrides can also be used. On the other hand, the film thickness of the magnetic layer protective layer is determined by the spacing loss at the time of magnetic recording / reproduction, but here it is 3 μm or less, preferably 2 μm or less. Further, in order to maintain the uniformity of the envelope during signal reproduction of one track, the surface roughness of the magnetic layer protective layer must be controlled, and the maximum surface roughness (Rt) is preferably 1 μm or less. Therefore, the size of the inorganic polishing fine particles must be at most 0.5 μm or less.

The content of the inorganic polishing fine particles is 0.1 wt.
% Or more and 5 wt% or less is preferable. The polishing effect on the magnetic head and the effect of reducing the contact area between the magnetic head and the composite disk (magnetic layer protective layer) are greater as the content is higher, but in a thin film having a thickness of 2 μm or less formed by the spin coat method. In order to control the surface roughness by tape polishing or the like, the smaller the content, the better. Therefore, the optimum content is in the range of 0.1 wt% to 3 wt%.

[0058]

As described above, according to the composite disc of the present invention as set forth in claim 1, on a disk-shaped transparent substrate,
In a composite disc in which an optical recording layer on which optical information is to be recorded, a protective layer for an optical recording layer, a magnetic layer having a predetermined shape, and a magnetic layer protective layer are sequentially laminated, the magnetic layer protective layer comprises:
By forming the solid lubricant and the liquid lubricant or the ultraviolet curable resin containing any one of them, the effect of the lubricant can be obtained, and the magnetic head to which a predetermined contact load is applied causes the contact traveling. Can also form a magnetic layer protective layer having stable running characteristics, and
A composite disk having highly reliable magnetic head running characteristics can be provided.

Further, according to the composite disc of the present invention as defined in claim 2, an optical recording layer on which optical information is to be recorded, a protective layer for the optical recording layer, and a predetermined layer are provided on a disk-shaped transparent substrate. In a composite disk in which a magnetic layer having a shape and a magnetic layer protective layer are sequentially laminated, the magnetic layer protective layer contains a solid lubricant and / or a liquid lubricant or one of them, and inorganic abrasive fine particles. Since it is made of UV curable resin, it has the effect of a lubricant, the contact area is reduced, and the polishing effect is obtained, and the magnetic head to which a predetermined contact load is applied has a stable running characteristic even when it is in contact. A magnetic layer protective layer can be formed, and thereby a composite disk having highly reliable magnetic head running characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing the configuration of a general composite disc.

FIG. 2 is a perspective view showing a schematic configuration of a tape polishing device for a composite disc.

FIG. 3 is a front view showing a schematic configuration of a sliding tester for a composite disk.

[Explanation of symbols]

 1 substrate 2 signal pit 3 optical recording layer 4 optical recording layer protective layer 5 magnetic layer 6 magnetic layer protective layer 10 composite disc 15 optical disc

Claims (2)

[Claims] 1. An optical recording layer on which optical information is to be recorded, a protective layer for an optical recording layer, a magnetic layer having a predetermined shape, and a magnetic layer protective layer are sequentially laminated on a disk-shaped transparent substrate. In the composite disc described above, the magnetic layer protection layer is formed of a solid lubricant, a liquid lubricant, or an ultraviolet curable resin containing any one of them. 2. An optical recording layer on which optical information is to be recorded, an optical recording layer protective layer, a magnetic layer having a predetermined shape, and a magnetic layer protective layer are sequentially laminated on a disk-shaped transparent substrate. In the composite disc described above, the magnetic layer protective layer is formed of an ultraviolet curable resin containing a solid lubricant and / or a liquid lubricant, and inorganic abrasive fine particles.