JPH07176109A - Composite disk - Google Patents

Abstract

PURPOSE:To prevent production of scratches and magnetic head crash on a magnetic layer containing UV-curing resin or protective film comprising UV curing resin for a magnetic layer even when a magnetic head on which specified contact load is applied is travelled in a contact state, and to obtain a composite disk having magnetic recording and reproducing characteristics with high reliability. CONSTITUTION:An optical recording layer 3 in which optical information is to be recorded, a protective layer 4, a magnetic layer 5, and at least a lubricating layer 7 are successively formed on a disk transparent substrate 1. The magnetic layer 5 having a specified shape is formed by curing a magnetic coating material essentially comprising a UV-curing resin. In this composite disk 11, the lubricating layer 7 consists of silicone oil.

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 lubricating layer on the layer and allowing good contact running of the magnetic head.

[0002]

2. Description of the Related Art A read-only optical disc which reads out an information signal recorded on an optical recording layer formed on a transparent substrate by using a laser beam can reproduce a large amount of the same information in a short time. Because of what it can do, it is now widespread. 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 disc by providing a recording area on the read-only optical disc in which a small amount of information can be added and recording management information therein. For example, in the case of a play-only optical disc for a game (hereinafter, also referred to as a game optical disc), when the game is interrupted midway and restarted again, the scene of the game at the time of interruption so that the game can be started from the interrupted scene. It is possible to record game management information such as numbers and game scores up to that point on the optical disc player, but I want to take the game optical disc to another location and restart the game with another optical disc player there. In this case, since the game management information is recorded in the optical disc player and not recorded in the game optical disc, it is not possible to resume from the previously interrupted scene.

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. 5 is a comparative example 1 which is a conventional composite disk.
3 is a partial cross-sectional view showing the configuration of FIG. In FIG. 5, 1 is a substrate, 2 is a signal pit, 3 is an optical recording layer, 4 is a protective layer, 5 is a magnetic layer, 13 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. On the optical recording layer 3, a protective layer 4 made of an ultraviolet curable resin is formed to form an optical disc 15. Further, a magnetic layer 5 for writing a small amount of rewritable information by a magnetic recording method is formed on the protective layer 4 (see the comparative example 2 of the conventional composite disc of FIG. 6). As described above, a magnetic layer protective film 6 made of resin may be formed on the magnetic layer 5 in order to prevent the magnetic layer 5 from being damaged by sliding of a magnetic head (not shown). Is configured. Magnetic recording / reproduction on the magnetic layer 5 is performed by a magnetic head (not shown).

[0007]

When a rewritable information is recorded / reproduced by providing a magnetic layer on an optical disk, the number of revolutions of the composite disk is usually low, and the surface wobbling of the composite disk is also caused. Since the optical disk is large because it has a basic structure, it is necessary to adopt a contact recording method in which a magnetic head is brought into contact with the composite disk in order to stably perform magnetic recording and reproduction.

Further, in the composite disc, the recording bit unit price of the optical recording layer is very low, and therefore it is necessary to make the recording bit unit price of the magnetic layer as low as possible. In the patent application (reference number 405001176) submitted on November 29, 2014,
We proposed a composite disk with a magnetic layer formed by applying a magnetic coating material containing an ultraviolet curable resin. Then, the applicant of the present application applies a magnetic coating mainly containing an ultraviolet curable resin onto a conventional optical disc to form a magnetic layer, and produces various kinds of composite discs. In this way, the durability of the magnetic recording / reproducing characteristics of the composite disk when the magnetic head was run was investigated.

According to this, when the magnetic layer and the magnetic head are brought into direct contact with each other to perform magnetic recording / reproducing, in order to obtain stable magnetic recording / reproducing characteristics, it is necessary to sufficiently increase the contact load applied to the magnetic head. Therefore, although sufficient magnetic recording and reproducing characteristics were obtained at the beginning of running the magnetic head, continuous use causes scratches in the magnetic layer due to friction between the magnetic layer and the magnetic head. at last,
It turns out that the magnetic head crashes. On the other hand, regarding the composite disc in which a magnetic layer protective film made of an ultraviolet curable resin is formed on the magnetic layer to protect the magnetic layer,
Similar examination was conducted, but it was similarly found that the magnetic head protective film and the magnetic layer were scratched by the contact running of the magnetic head for a long time, and eventually the magnetic head crashed.

Therefore, the present invention has been made by paying attention to the above points, and in a composite disk, even when the composite disk is in contact with a magnetic head to which a predetermined contact load is applied,
It is possible to prevent scratches and magnetic head crashes in a magnetic layer mainly containing an ultraviolet curable resin or a magnetic layer protective film made of an ultraviolet curable resin, thereby providing a composite disk having highly reliable magnetic recording / reproducing characteristics. The purpose is to do.

[0011]

SUMMARY OF THE INVENTION A composite disk of the present invention comprises an optical recording layer for recording optical information made of aluminum on a transparent substrate on a disk made of polycarbonate resin and the optical recording layer. A protective layer made of an ultraviolet curable resin for protecting the recording layer, and a magnetic layer having a predetermined shape, in which additional information is recorded, which is formed by applying a magnetic coating material mainly composed of the ultraviolet curable resin and magnetic powder and curing the applied magnetic paint. In a composite disk in which at least a lubricating layer for sequentially protecting the magnetic layer during contact travel of a magnetic head is sequentially laminated, the lubricating layer is formed of silicone oil, thereby achieving the above object. It is a thing.

The composite disk of the present invention is a
An optical recording layer on which optical information is to be recorded, made of aluminum, a protective layer made of an ultraviolet curable resin for protecting the optical recording layer, and additional information are formed on a transparent substrate on a disk made of a bone resin. Is recorded, a magnetic layer having a predetermined shape formed by applying a magnetic coating mainly composed of an ultraviolet curable resin and magnetic powder and then curing it, and at least a lubricant for protecting the magnetic layer when the magnetic head is in contact and running. In a composite disc in which layers are sequentially laminated, the lubricating layer is formed of at least one of dimethylpolysiloxane, diphenylpolysiloxane, and methylphenylpolysiloxane, thereby achieving the above object. is there.

Further, the composite disc of the present invention is defined in claim 2.
In the composite disc according to the above paragraph, the dimethylpolysiloxane, the diphenylpolysiloxane or the methylphenylpolysiloxane has a viscosity of 20 at 25 ° C.
The above-mentioned object is achieved by setting the volatile content to 1% or less.

[0014]

The UV curable resin constituting the magnetic layer or the UV curable resin constituting the magnetic layer protective film has good compatibility with dimethylpolysiloxane, diphenylpolysiloxane or methylphenylpolysiloxane. Dimethyl polysiloxane, diphenyl polysiloxane or methyl phenyl polysiloxane, on the magnetic layer or the magnetic layer protective film,
When it is formed as a lubricating layer, it easily penetrates into the pores of the respective ultraviolet curable resins, is well fitted to the surface of the magnetic layer or the magnetic layer protective film, and covers the surface. Even if the magnetic head comes into contact with a predetermined contact load, the lubricating layer is not broken and the friction coefficient between the magnetic layer or the magnetic layer protective film and the magnetic head is kept constant.

Further, since the viscosity of dimethylpolysiloxane, diphenylpolysiloxane or methylphenylpolysiloxane is in the range of 20 to 1000 cSt,
Since the fluidity at the time of application is appropriate, a lubricating layer with a uniform film thickness is formed, and the shearing force is also appropriate, solid contact between sliding surfaces does not occur even when contact sliding with a magnetic head, and Holds good friction force.

[0016]

EXAMPLE A composite disk was manufactured, and the magnetic recording / reproducing characteristics were evaluated and the sliding test was conducted. Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 shows Embodiment 1 of the composite disk of the present invention.
3 is a partial cross-sectional view showing the configuration of FIG. In FIG. 1, 7 indicates a lubricating layer and 11 indicates a composite disk. The same reference numerals are given to those common to the above-described conventional example, and the description thereof will be omitted. First, the outline of the configuration of the optical disc 15 will be described. 120mm diameter transparent polycarbonate
A signal pit 2 is formed on a substrate 1 made of a Bonnet resin by an injection molding method using a stamper. The entire surface of the signal pit 2 has a thickness of 100 n by a sputtering method.
An Al film of m is formed as the optical recording layer 3. On the optical recording layer 3, an ultraviolet curable resin made of, for example, trimethylpropane triacrylate is applied by a spin coat method and then cured by ultraviolet rays to have a thickness of 10
A protective layer 4 of μm is formed.

A magnetic paint mainly containing an ultraviolet curable resin (this will be described later) is applied to the optical disk 15 having the above-mentioned structure by a screen printing method (the screen is a Tetron type 380 mesh, Emulsion is applied to a thickness of 12 μm, inner diameter 39 mm, outer diameter 118
mm-shaped doughnut-shaped opening), and a magnetic paint film having a predetermined shape is formed. This magnetic coating film is cured by irradiation with ultraviolet rays to form a magnetic layer 5 having a thickness of 15 μm.
Is formed. Since the surface of the magnetic layer 5 has a relatively large undulation, it is polished and flattened by using a polishing tape to obtain a magnetic layer 5 having a film thickness of 5 μm and a surface roughness Rmax of 1.2 μm. . The thickness of the magnetic layer 5 was measured by breaking a composite disk manufactured under the same conditions and observing the broken surface. The surface roughness Rmax was measured using a Talysurf surface roughness meter.

On this magnetic layer 5, 1% of silicone oil diluted to about 0.25% with n-hexane as a solvent was used.
The seed methyl phenyl polysiloxane (KF-54:
A trade name, manufactured by Shin-Etsu Chemical Co., Ltd., was applied by a spin coat method to form a lubricating layer 7 having a film thickness of about 10 nm, and a composite disk 11 of Example 1 was obtained. The viscosity of the silicone oil was 440 cSt and the volatile content was 0.5%. Here, the viscosity was measured by a cone plate type rotational viscometer. The volatile matter was kept at 150 ° C. for 24 hours and calculated from the weight change before and after.

Next, the magnetic layer 5 of the composite disk 11
Then, after magnetic recording was performed by the magnetic head, the signal was reproduced and the reproduction output and C / N were evaluated. The reproduction output was 200 mV and the C / N was 48 dB. In addition,
The conditions for magnetic recording and reproduction are as follows. A ferrite head having a track width of 200 μm and a gap length of 7 μm was used as the magnetic head. The recording tracks are concentric and the track pitch is 600 μm. The number of rotations of the composite disk 11 at the time of recording / reproducing is 360 rpm, which is 62.5 k.
A rectangular wave signal of Hz was recorded and reproduced. The reproduction output is the output from a head amplifier that has been subjected to a predetermined amplification, and C / N is obtained from the waveform of a spectrum analyzer.

This composite disk 11 was mounted on a composite disk sliding tester (described later), and a sliding test using a magnetic head was conducted. The coefficient of friction at the beginning of sliding was 0.45, and the coefficient of friction 1 hour after sliding was 0.50. The running state of the magnetic head one hour after sliding is stable running,
At this time, no scratch was generated on the magnetic layer 5. The sliding test conditions were as follows. The contact load of the magnetic head is 3g
The rotation speed of the composite disk 11 is 330 rpm, and the sliding position of the magnetic head is a track having a radius of 40 mm on the composite disk 11. Next, one hour after sliding, the reproduction output and the C / N were measured, and the result was the same as the initial value.

Next, an 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 (11, 12, 13) is a composite disk, 21 is a clamp, 22 is a spindle, and 23
Is a central axis of rotation, 24 is a magnetic head, 25 is a suspension, 26 is a head fixing portion, 27 is a load cell, 28 is an arm, and 29 is a surface plate.

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 11 is mounted on the protrusion of the spindle 22 which penetrates the 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 vertically and horizontally (spindle 2
It is configured to be movable in the direction of the rotation center axis 23 of 2). At a predetermined position on the upper surface 29a of the surface plate 29,
The dosels 27 are arranged and fixed. 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 No. 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 11. The position of the magnetic head 24 on the composite disk 11 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, an outline of the sliding test will be described. The composite disk 11 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 11, and a frictional force acts in the rotating direction of the composite disk 11. 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.

Next, the magnetic paint used to form the magnetic layer 5 will be described. The main component of the magnetic paint is an ultraviolet curable resin, and acrylic acid ester-based trimethylpropane triacrylate (TMPTA: manufactured by Nippon Kayaku Co., Ltd.) is used as the magnetic paint. Fe ₂ O
₃ CMX-473 (trade name, manufactured by Toda Kogyo Co., Ltd.)
The concentration of the magnetic powder is set to 15 wt%, a higher fatty acid ester (glycerin monofatty acid ester) is used as the dispersant, and Darocur-42 is used as the photo-curing agent.
65 (trade name, manufactured by Merck Japan Ltd.) was used.
A predetermined amount of each was mixed and sufficiently kneaded to disperse the magnetic powder to prepare a magnetic paint.

<Example 2> On the magnetic layer 5, dimethylpolysiloxane (WF-3) which is one kind of silicone oil diluted with n-hexane as a solvent to about 0.25%.
0: Product name, Toray Dow Corning Silicone Co., Ltd.
Composite disk 11 was obtained in the same manner as in Example 1 except that the lubricant layer 7 having a film thickness of about 10 nm was formed by applying a spin coating method. The viscosity of silicone oil is 1
40 cSt, volatile matter was 0.5%. A sliding test similar to that in Example 1 was performed on this composite disk 11. The coefficient of friction at the beginning of sliding was 0.40, and the coefficient of friction 1 hour after sliding was 0.42. The running state of the magnetic head after one hour of sliding was stable running, and no scratch was generated on the magnetic layer 5 at this time.

Example 3 On the magnetic layer 5, n-hexane was used as a solvent and diluted to about 0.25%, and the viscosity was 10.
A methylphenylpolysiloxane having a concentration of 0 cSt and a volatile content of 0.5% was applied by a spin coat method to give about 1
A composite disk 11 was obtained in the same manner as in Example 1 except that the lubricating layer 7 having a film thickness of 0 nm was formed. A sliding test similar to that in Example 1 was performed on this composite disk 11. The coefficient of friction at the beginning of sliding was 0.45, and the coefficient of friction 1 hour after sliding was 0.49. The running state of the magnetic head after one hour of sliding was stable running, and no scratch was generated on the magnetic layer 5 at this time.

Example 4 On the magnetic layer 5, n-hexane was used as a solvent and diluted to approximately 0.25%, and the viscosity was 66.
A methylphenylpolysiloxane having a concentration of 0 cSt and a volatile content of 0.5% was applied by a spin coat method to give about 1
A composite disk 11 was obtained in the same manner as in Example 1 except that the lubricating layer 7 having a film thickness of 0 nm was formed. A sliding test similar to that in Example 1 was performed on this composite disk 11. The coefficient of friction at the beginning of sliding was 0.80, and the coefficient of friction after one hour of sliding was 0.83. The running state of the magnetic head after one hour of sliding was stable running, and no scratch was generated on the magnetic layer 5 at this time.

<Embodiment 5> On the magnetic layer 5, n-hexane was used as a solvent and diluted to about 0.25%, and the viscosity was 52.
A methylphenylpolysiloxane having a concentration of 0 cSt and a volatile content of 0.5% was applied by a spin coat method to give about 1
A composite disk 11 was obtained in the same manner as in Example 1 except that the lubricating layer 7 having a film thickness of 0 nm was formed. A sliding test similar to that in Example 1 was performed on this composite disk 11. The coefficient of friction at the beginning of sliding was 0.70, and the coefficient of friction after 1 hour of sliding was 0.78. The running state of the magnetic head after one hour of sliding was stable running, and no scratch was generated on the magnetic layer 5 at this time.

Example 6 On the magnetic layer 5, n-hexane was used as a solvent and diluted to about 0.25%, and the viscosity was 52.
A spin-coating mixture of a methylphenylpolysiloxane having a concentration of 0 cSt and a volatile content of 0.5% and a dimethylpolysiloxane having a viscosity of 140 cSt and a volatile content of 0.5% at a weight ratio of 5: 1 was used. Apply by the method
A composite disk 11 was obtained in the same manner as in Example 1 except that the lubricating layer 7 having a film thickness of 0 nm was formed. A sliding test similar to that in Example 1 was performed on this composite disk 11. The coefficient of friction at the beginning of sliding was 0.40, and the coefficient of friction after 1 hour of sliding was 0.43. The running state of the magnetic head after one hour of sliding was stable running, and no scratch was generated on the magnetic layer 5 at this time.

Example 7 On the magnetic layer 5, n-hexane was used as a solvent and diluted to about 0.25%, and the viscosity was 32.
A diphenylpolysiloxane having a volatile content of 0 cSt and a volatile content of 0.5% was applied by a spin coat method to obtain about 10 n.
A composite disk 11 was obtained in the same manner as in Example 1 except that the lubricating layer 7 having a thickness of m was formed. This composite disc 11
The same sliding test as in Example 1 was performed. The coefficient of friction at the beginning of sliding was 0.42, and the coefficient of friction 1 hour after sliding was 0.44. The running state of the magnetic head after one hour of sliding was stable running, and no scratch was generated on the magnetic layer 5 at this time.

Example 8 On the magnetic layer 5, n-hexane was used as a solvent and diluted to about 0.25%, and the viscosity was 60.
A composite disk 11 was prepared in the same manner as in Example 1 except that dimethylpolysiloxane having a cSt content of 0.5% and a volatile content of 0.5% was applied by a spin coat method to form a lubricating layer 7 having a thickness of about 10 nm. Got A sliding test similar to that in Example 1 was performed on this composite disk 11. The coefficient of friction at the beginning of sliding was 0.35, and the coefficient of friction 1 hour after sliding was 0.60. The friction coefficient gradually increased up to 45 minutes until the sliding time reached 0.60, but thereafter, it hardly changed. The running state of the magnetic head after 1 hour of rubbing after 1 hour was stable running, and no scratch was generated on the magnetic layer 5 at this time.

<Embodiment 9> FIG. 2 is a partial sectional view showing the structure of Embodiment 8 of the composite disk of the present invention. In FIG. 2, 6 indicates a magnetic layer protective film, and 10 indicates a composite disk. The same reference numerals are given to those common to the above-described conventional example, and the description thereof will be omitted. A magnetic layer 5 having a film thickness of 12.5 μm is formed, and on this magnetic layer 5,
A UV-curable resin made of urethane acrylate (which will be described later) is applied by a spin coat method and then irradiated with UV rays to be cured to form a magnetic layer protective film 6 having a thickness of 2 μm. , On the surface of the magnetic layer protective film 6
The surface roughness Rmax to 0.4 μm,
On this magnetic layer protective film 6, n-hexane is used as a solvent,
Dimethylpolysiloxane (KF) with a viscosity of 440 cSt and a volatile content of 0.5% diluted to approximately 0.25%.
-54) is applied by a spin coat method to give a thickness of about 10 nm.
A composite disk 10 was obtained in the same manner as in Example 1 except that the lubricating layer 7 having the above film thickness was formed.

Next, the magnetic layer 5 of the composite disk 10
Then, after magnetic recording was performed by the magnetic head, the signal was reproduced and the reproduction output and C / N were evaluated. The reproduction output was 310 mV and the C / N was 50 dB. next,
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 0.42, and the coefficient of friction after one hour of sliding was 0.47. The running state of the magnetic head after one hour of sliding was stable running, and at this time, no scratch was generated on the magnetic layer. Next, one hour after sliding, the reproduction output and C / N
As a result of measurement, it was the same as the initial value.

Here, the ultraviolet curable resin used for forming the magnetic layer protective film 6 will be described. 30 wt% of urethane acrylate monomer (uX-2201: trade name, manufactured by Nippon Kayaku Co., Ltd.), 20 wt% of R-551 (trade name, manufactured by Nippon Kayaku Co., Ltd.), and 50 wt% of 1 .6 Hexanedio-
Lugia acrylate (HDDA: trade name, Nippon Kayaku Co., Ltd.)
Manufactured by Darocur 1173 as a photo-curing agent.
(Trade name: manufactured by Merck Japan Ltd.) was added to prepare an ultraviolet curable resin.

<Comparative Example 1> FIG. 5 is a partial sectional view showing the structure of Comparative Example 1 which is a conventional composite disk. The surface of the magnetic layer 5 is polished and flattened using a polishing tape,
A composite disk 13 was obtained in the same manner as in Example 1 except that a magnetic layer 5 having a film thickness of 5.4 μm and a surface roughness Rmax of 1.3 μm was formed, and no lubricating layer was formed on the magnetic layer 5. . Next, after magnetic recording was performed on the magnetic layer 5 of the composite disk 13 by the magnetic head, the signal was reproduced and the reproduction output and C / N were evaluated. The reproduction output was 190 mV and the C / N was 40 dB.

Next, the composite disk 13 was mounted in a composite disk sliding tester, and a sliding test using a magnetic head was conducted. The friction coefficient at the beginning of sliding was 0.42, and the magnetic head crashed after 55 minutes of sliding. The friction coefficient after one hour of sliding could not be measured because the stick slip of the magnetic head was too large. At this time, many large scratches were generated on the magnetic layer. Next, one hour after the sliding, the reproduction output and the C / N were measured. As a result, it was impossible to obtain stable running due to stick slip of the magnetic head, and the measurement was impossible.

<Comparative Example 2> FIG. 6 is a partial sectional view showing the structure of Comparative Example 2 which is a conventional composite disk. Figure 6
In FIG. 6, 6 is a magnetic layer protective film, and 12 is a composite disk. The same reference numerals are given to those common to the above-described conventional example, and the description thereof will be omitted. The surface of the magnetic layer 5 is polished and flattened with a polishing tape to obtain a magnetic layer 5 having a film thickness of 5.1 μm and a surface roughness Rmax of 1.1 μm. The UV curable resin composed of urethane acrylate used in Example 9 was applied by a spin coat method and then irradiated with UV rays to be cured to form a magnetic layer protective film 6 having a thickness of 2 μm.
The same as Example 1 except that the surface of the magnetic layer protective film 6 was subjected to tape polishing treatment so that the surface roughness Rmax was 0.4 μm and no lubricating layer was formed on the magnetic layer protective film 6. A composite disk 12 was obtained.

Next, the magnetic layer 5 of the composite disk 12
Then, after magnetic recording was performed by the magnetic head, the signal was reproduced and the reproduction output and C / N were evaluated. The reproduction output was 180 mV and the C / N was 41 dB. next,
This composite disk 12 was mounted on a composite disk sliding tester, and a sliding test using a magnetic head was performed. The friction coefficient at the initial stage of sliding was 0.50, and the magnetic head crashed after 55 minutes of sliding. When the friction coefficient after 1 hour of sliding was measured, the stick-slip was large, and therefore the fluctuation was large, but an average value of about 1.15 was obtained. This time,
Many large scratches were generated on the magnetic layer 5. Next, as a result of measuring the reproduction output and C / N one hour after the sliding, it was impossible to measure because the stick slip was too large.

The following table summarizes the results of the sliding test for each of the above samples.

[0041]

[Table 1]

The results of the sliding test shown in each of the examples show that the friction coefficient before and after the sliding test is a good value that does not exceed 1, and that the friction coefficient increases as the sliding time increases. However, it maintained a stable value, which enabled stable running of the magnetic head. Further, the magnetic recording / reproducing characteristics measured (Examples 1 and 9) also show that the magnetic recording / reproducing characteristics are stable even if the sliding time is increased. On the other hand, in each of the comparative examples, before the sliding time reaches 1 hour,
It can be seen that a head crash occurs and the magnetic recording / reproducing characteristics are impaired.

For Example 1 and Comparative Example 1, FIG. 6 shows a chart of a sliding test. As shown in FIG. 6, in Example 1, there was an initial increase in the friction coefficient in order to adapt to the lubricating layer at the initial sliding stage, but thereafter, there was little fluctuation in the friction coefficient and a stable value was exhibited. I understand that. On the other hand, in Comparative Example 1, not only the initial increase in the friction coefficient but also the increase in the friction coefficient with the passage of the sliding time were observed.
Moreover, it can be seen that there is a large variation in the friction coefficient indicating stick-slip, and a head crash occurs 1 hour before sliding.

The effect of forming the lubricating layer by any one of dimethylpolysiloxane, diphenylpolysiloxane or methylphenylpolysiloxane which is a silicone oil has been described above. Further, the effect of the viscosity of the silicone oil will be described. To do. If the viscosity of the silicone oil is too high, it is difficult to control the film thickness when applying the silicone oil, and it is difficult to form a lubricating layer having a uniform film thickness. Regarding the slidability, the frictional force increases because the shearing force of the lubricating layer is high. On the other hand, if the viscosity of the silicone oil is too low, the components have a low degree of polymerization, which deteriorates the heat resistance of the lubricating layer formed thereby and increases the volatility of the components, which is not preferable. Regarding the slidability, the frictional force decreases due to the smaller shearing force of the lubricating layer, but during sliding, it becomes difficult to hold the lubricating layer between the two opposing sliding surfaces, Solid contact between the moving surfaces occurs, resulting in an increased frictional force, which is not preferable.

The viscosity of the silicone oil at 25 ° C. is in the range of 20 CcSt to 1000 cSt,
Good lubrication layer formation and slidability. Furthermore, 100 cSt
In the range from 1 to 500 cSt, there are many kinds of silicone oil, and selection becomes easy. If the volatile content is high,
Due to the effect of frictional heat generated by long-time contact between the magnetic head and the magnetic layer (or the magnetic layer protective film),
The film thickness of the lubricating layer becomes lower than the optimum value, the lubricating layer is apt to be broken, and the lubricating effect is reduced. Within the experimental range, volatile matter of 1% or less is good,
Further, when it is 0.5% or less, there is no deterioration and modification, and it is more preferable.

[0046]

As described above, the composite disk of the present invention according to claim 1 is such that an optical recording layer on which optical information is to be recorded, a protective layer, and mainly an ultraviolet ray are formed on a disk-shaped transparent substrate. In a composite disk in which a magnetic layer having a predetermined shape formed by applying a magnetic coating material made of a cured resin and then curing the layer, and at least a lubricating layer are sequentially laminated, the lubricating layer is a silicone layer.
Since the magnetic head is formed of a magnetic oil, even when the magnetic head to which a predetermined contact load is applied is in contact with the magnetic head, the magnetic layer mainly containing the ultraviolet curable resin or the magnetic layer protective film made of the ultraviolet curable resin causes a scratch and a magnetic field. It is possible to prevent a head crash, thereby providing a composite disk having highly reliable magnetic recording / reproducing characteristics.

Further, the composite disk of the present invention according to claim 2 is a magnetic coating comprising an optical recording layer on which optical information is to be recorded, a protective layer, and an ultraviolet curable resin mainly on a disk-shaped transparent substrate. In a composite disk in which a magnetic layer having a predetermined shape formed by applying and then being cured, and at least a lubricating layer are sequentially laminated, any one of dimethylpolysiloxane, diphenylpolysiloxane, and methylphenylpolysiloxane can be used as the lubricating layer. With the magnetic head having a predetermined contact load applied, it is possible to prevent the occurrence of scratches in the magnetic layer mainly containing the ultraviolet curable resin or the magnetic layer protective film composed of the ultraviolet curable resin, even if the magnetic head is applied with a predetermined contact load. It is possible to prevent a magnetic head crash, thereby providing a composite disk having highly reliable magnetic recording / reproducing characteristics.

A composite disk of the present invention according to claim 3 is the composite disk according to claim 2, wherein the dimethylpolysiloxane, the diphenylpolysiloxane or the methylphenylpolysiloxane has a viscosity of 20 to 25 ° C. 1000 cSt with 1% volatiles
By doing the following, it is possible to form a lubricating layer having a uniform film thickness and an appropriate friction coefficient. Therefore, even if the composite disk is in contact with a magnetic head to which a predetermined contact load is applied, To provide a composite disk having a magnetic layer containing an ultraviolet curable resin or a magnetic layer protective film made of an ultraviolet curable resin, which can prevent a scratch and a magnetic head crash from occurring, thereby having a highly reliable magnetic recording / reproducing characteristic. Can be done.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a configuration of a first embodiment of a composite disc of the present invention.

FIG. 2 is a partial cross-sectional view showing the configuration of Example 9 of the composite disc of the present invention.

FIG. 3 is a front view showing a schematic configuration of a friction tester for a composite disc.

FIG. 4 is a graph showing the relationship between frictional force and sliding time in Example 1 and Comparative Example 1 of the composite disc of the present invention.

FIG. 5 is a partial cross-sectional view showing the configuration of Comparative Example 1 which is a conventional composite disk.

FIG. 6 is a partial cross-sectional view showing the structure of a comparative example 2 which is a conventional composite disk.

[Explanation of symbols]

 1 substrate 2 signal pit 3 optical recording film 4 protective layer 5 magnetic layer 6 magnetic layer protective film 7 lubrication layer 10 composite disc 11 composite disc 12 composite disc 13 composite disc 15 optical disc

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Kondo 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan, Ltd.

Claims (3)

[Claims] 1. A predetermined shape formed on a disk-shaped transparent substrate by applying an optical recording layer on which optical information is to be recorded, a protective layer, and a magnetic coating material mainly composed of an ultraviolet curable resin and then curing it. 7. A composite disc in which the magnetic layer and at least a lubricating layer are sequentially laminated, wherein the lubricating layer is formed of silicone oil. 2. A predetermined shape formed on a disk-shaped transparent substrate by applying an optical recording layer on which optical information is to be recorded, a protective layer, and a magnetic coating material mainly composed of an ultraviolet curable resin and curing the applied coating material. In the composite disk in which the magnetic layer of, and at least a lubricating layer are sequentially laminated, the lubricating layer is formed of dimethylpolysiloxane, diphenylpolysiloxane or methylphenylpolysiloxane,
A composite disc formed by at least one of them. 3. The composite disc according to claim 2, wherein the dimethylpolysiloxane, the diphenylpolysiloxane or the methylphenylpolysiloxane is 25
A composite disk having a viscosity at 20 ° C. of 20 to 1000 cSt and a volatile content of 1% or less.