JPH087347A - Manufacture of optical disk - Google Patents

Abstract

PURPOSE:To improve productivity by reducing the fabrication cost and reduce the amount of waste liquid generated in the fabrication process in order to make contribution to protection of environment of the earth. CONSTITUTION:Under the condition that the ultraviolet-curing type resin 4 is supplied to form a protection film at the surface of an optical disk substrate 1, the ultraviolet-curing resin 4 rejected when the optical disk substrate 1 is rotated is collected by a resin receiving tray 10. The collected resin 4 is filtered with a second filter 17 for recyclic use. The protection film formed by the ultraviolet-curing resin U may be a recording film or a protection film formed on the reflecting film or may be a charged protection film formed on the laser beam irradiating surface of the optical disk substrate. Moreover, a magneto- optical disk substrate may be used in place of the optical disk substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk, and more particularly to a method for manufacturing an optical disk which enables reuse of an ultraviolet curable resin applied to form a protective film.

[0002]

2. Description of the Related Art In a magneto-optical recording system, the temperature of a magnetic thin film is partially raised above a Curie point or a temperature compensation point, and the coercive force in this portion is eliminated to magnetize the magnetic thin film in the direction of an externally applied recording magnetic field. It is based on the principle of reversing the direction of an image, and is being put to practical use in an optical file system, an external storage device of a computer, a recording device for audio and video information, and the like.

A magneto-optical disk used in this magneto-optical recording system has an easy axis of magnetization in a direction perpendicular to the film surface on one main surface 101a of a transparent substrate 101 made of polycarbonate as shown in FIG. The recording portion 1 is formed by stacking a recording magnetic layer (for example, a rare earth-transition metal alloy amorphous thin film) having a large magneto-optical effect, a reflecting layer, and a dielectric layer.
In order to prevent the corrosion of the recording portion 102, it is known that the recording portion 102 is formed so as to cover a protective film 103 made of an ultraviolet curable resin or the like.

Further, in such a magneto-optical disk, in order to prevent the substrate 101 from being scratched or charged, the main surface 101a of the substrate 101 on which the recording portion 102 is formed is opposite to the laser light irradiation surface 101b. Antistatic protective film 1
In some cases, 04 is formed. The antistatic protective film 104 is also formed of an ultraviolet curable resin or the like.

The protective film for a magneto-optical disk as described above is generally formed by applying an ultraviolet curable resin by a so-called spin coating method and then irradiating it with ultraviolet rays to cure it.

The spin coating method is a method of forming a coating film as follows. That is, as shown in FIG. 3A, a magneto-optical disk substrate 105 having a recording portion formed on a transparent substrate is rotated at a low speed, for example, in the direction indicated by an arrow m ₁ in the figure, and on one main surface 105a thereof. An ultraviolet curable resin 107 is supplied from the resin supply port 106 to the vicinity of the central portion of the. Then, the ultraviolet curable resin 107 is applied in a circle in the vicinity of the center of the one main surface 105a of the magneto-optical disk substrate 105.

Next, as shown in FIG. 3B, when the magneto-optical disk substrate 105 is rotated at a high speed in the direction indicated by an arrow m ₁ in the figure, the ultraviolet curable resin 107 becomes as shown in the figure. A coating film is formed on the entire main surface 105a of the magneto-optical disk substrate 105 so as to spread uniformly.

At this time, the magneto-optical disk substrate 10
The extra UV curable resin 107 is shaken off by the high speed rotation of 5, and the extra UV curable resin 1 is removed as shown in the figure.
07a scatters from the magneto-optical disk substrate 105.

An example of a magneto-optical disk manufacturing apparatus to which the above spin coating method is applied is shown in FIG. The magneto-optical disk manufacturing apparatus described above mainly holds a magneto-optical disk substrate 105 having a recording section formed on a transparent substrate and can rotate the holding section 1.
10, a drive unit 111 for rotating the holding unit 110, a supply tank 113 filled with the ultraviolet curable resin 107,
A pipe 114 for supplying the ultraviolet curable resin 107 in the supply tank 113 to the resin supply port 106 and a filter 115 arranged in the middle of the pipe 114 for filtering the ultraviolet curable resin 107.

In order to manufacture a magneto-optical disk with the above-mentioned magneto-optical disk manufacturing apparatus, first, the control section 112 is used.
The holding unit 110 is rotated by the driving unit 111 connected to the magneto-optical disk substrate 105 to rotate the magneto-optical disk substrate 105 at a low speed in a predetermined direction. When the protective film is formed, the magneto-optical disk substrate 105 is placed with the recording section side facing upward and the holding section 11 is formed.
When the antistatic protective film is formed on the holding unit 110, the magneto-optical disk substrate 105 may be placed on the holding unit 110 with its transparent substrate side facing upward.

Then, in this state, a pressure as shown by an arrow P ₁ in the drawing is applied to the ultraviolet curable resin 107 in the supply tank 113, and a predetermined amount of the ultraviolet curable resin 107 is pushed out into the pipe 114 so that the pipe 114. After being filtered by a filter 115 disposed in the middle part, the resin is supplied from the resin supply port 106 onto the magneto-optical disk substrate 105.

Next, the controller 112 is adjusted to adjust the drive unit 11.
1 is adjusted and the rotation of the holder 110 is increased to rotate the magneto-optical disk substrate 105 at high speed. Then, the ultraviolet curable resin 107 on the magneto-optical disc substrate 105 spreads over the entire surface of the magneto-optical disc substrate 105, and the ultraviolet curable resin 1
The coating film No. 07 is formed on the entire surface of the magneto-optical disk substrate 105.

At this time, the surplus portion of the ultraviolet curable resin 107 on the magneto-optical disk substrate 105 is shaken off by the rotation of the magneto-optical disk substrate 105, and the magneto-optical disk substrate 1
It will be scattered from 05. Therefore, in the above-described magneto-optical disk manufacturing apparatus, a substantially box-shaped resin tray 117 having an opening 116 on the resin supply port 106 side and surrounding the magneto-optical disk substrate 105 held by the holder 110 is arranged. ing. That is, the ultraviolet curable resin 107 scattered by the rotation of the magneto-optical disk substrate 105 is collected in the resin tray 117.

A hole 118 is provided at the bottom of the resin tray 117, and the hole 118 and the waste liquid tank 119 are provided.
Are connected by a pipe 120, and a resin tray 117
The ultraviolet curable resin 107 collected in the above is collected in the waste liquid tank 119 through the pipe 120. The ultraviolet curable resin 107 thus collected in the waste liquid tank 119 is discarded as a waste liquid.

[0015]

By the way, in the magneto-optical disk, it is required that the protective film is formed uniformly on the entire surface of the magneto-optical disk. In particular, if coating unevenness is present in the antistatic protective film formed on the laser light irradiation surface in order to prevent the substrate from being scratched or charged, a servo error during reproduction will occur.

Therefore, when the coating film of the ultraviolet curable resin forming the protective film is formed by the above method, the amount of the ultraviolet curable resin supplied onto the magneto-optical disk is required to form the protective film. The amount is set to be sufficiently larger than the above amount to prevent uneven coating.

That is, most of the supplied UV-curable resin is shaken off by the rotation of the magneto-optical disk, and the surplus UV-curable resin is collected in the resin tray, collected in the waste liquid tank, and discarded as waste liquid. Becomes
In the actual manufacturing, since the amount of the ultraviolet curable resin that is 10 times or more the amount required to form the protective film is supplied, the utilization rate of the ultraviolet curable resin is 10%. It becomes the following.

Therefore, when the coating film of the ultraviolet curable resin forming the protective film is formed by the above method, the manufacturing cost becomes high and the productivity is not good. In addition, a large amount of waste liquid is produced during manufacturing, which is not preferable from the viewpoint of global environment protection.

Therefore, according to the present invention, it is possible to reuse the ultraviolet curable resin, reduce the manufacturing cost and improve the productivity, and reduce the amount of waste liquid at the time of manufacturing to manufacture an optical disk. The purpose is to provide a method.

[0020]

In order to achieve the above object, the present invention provides a method of manufacturing an optical disc in which a UV-curable resin is applied by a spin coating method to form a protective film, and the UV-cured resin is shaken off by rotation. The mold resin is collected and reused through a filter.

In the present invention, the protective film may be a protective film formed on the recording film or the reflective film, or an antistatic protective film formed on the laser light irradiation surface of the optical disc substrate.

Further, in the present invention, the optical disk may be a magneto-optical disk.

[0023]

In the method of manufacturing an optical disk of the present invention, the ultraviolet curable resin that is shaken off when applied by spin coating is collected and reused through a filter, which reduces the manufacturing cost. At this time, the UV curable resin is reused after being filtered by a filter to remove impurities such as dust, and thus does not deteriorate the characteristics of the manufactured optical disc.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk manufacturing apparatus to which the optical disk manufacturing method of the present invention is applied will be described below in detail with reference to the drawings. The optical disk manufacturing apparatus of this embodiment is shown in FIG.
As shown in (1), the optical disc substrate 1 having a recording portion formed of a recording film, a reflective film, etc. is mainly held on a transparent substrate,
A rotatable holding unit 2, a driving unit 3 for rotating the holding unit 2, a supply tank 5 filled with an ultraviolet curable resin 4, and an ultraviolet curable resin 4 in the supply tank 5 to a resin supply port 7. From the supply pipe 6 and the first pump 20 arranged in the middle of the pipe 6 to suck up the ultraviolet curable resin 4, and the first filter 8 arranged in the middle of the pipe 6 to filter the ultraviolet curable resin 4 Become.

Since the first filter 8 is for finally removing dust and the like of the ultraviolet curable resin 4, the first filter 8 has a filtering particle size of 0.2 μm.
I am using something of a degree. Further, the first pump 20
Is for determining the supply amount of the ultraviolet curable resin 4 to be supplied onto the optical disk substrate 1, the first pump 20
As the diaphragm pump, a diaphragm pump with a good conveyance amount accuracy is used.

In the optical disk manufacturing apparatus of this embodiment, the holding portion 2 has the opening 9 on the resin supply port 7 side.
A substantially box-shaped resin tray 10 is arranged so as to surround the optical disk substrate 1 held by the. In addition, the resin tray 1
A hole 11 is provided at the bottom of 0, and the hole 11 and the recovery tank 13 are connected by a pipe 12.

Further, in the optical disk manufacturing apparatus of this embodiment, a new liquid tank 14 filled with new ultraviolet curable resin 4 is also provided.

Then, pipes 15a and 15b extend from the recovery tank 13 and the new liquid tank 14, respectively, and these are merged into one via a three-way valve (not shown) on the way to the second pump 16 as the pipe 15. It is connected. A diaphragm pump is used as the second pump 16, but the first pump is not required to have a high accuracy in the transfer amount.
A bellows pump or the like, which has a larger transport amount than the pump 20 of FIG.

The pipe 15 is connected to the supply tank 5 via a second filter 17 in the middle. Since the second filter 17 is for almost removing impurities such as dust in the ultraviolet curable resin 4 to be reused, a filter having a filtration particle size of 2.5 μm and a filter having a filtration particle size of 1 μm are used. It is assumed that they are sequentially arranged in the inflow direction of the ultraviolet curable resin.

The inventors of the present invention investigated the proportion of impurities in the ultraviolet-curable resin used once when manufacturing the optical disk manufacturing apparatus of this embodiment. That is, when the once used ultraviolet curable resin was filtered with a filter having a filtration particle size of 1 μm, the filter was significantly clogged. Therefore, as the second filter 17 for filtering the ultraviolet curable resin to be reused, one having a filter particle size of 2.5 μm and a filter particle size of 1 μm is sequentially arranged in the ultraviolet curable resin inflow direction is used. I decided.

Further, the supply tank 5, the recovery tank 13,
The fresh liquid tank 14 is arranged in a tank box 18 which is shielded from light, and the load cells 19a, 19b, and
The weight is controlled by 19c.

In the optical disk manufacturing apparatus of this embodiment, most of the members in contact with the ultraviolet curable resin 4 are made of polytetrafluoroethylene (PTFE) and tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA). It was formed (however, some joints were made of stainless steel), and WCDS (model name) manufactured by Japan Millipore was used as the first pump 20. As the second pump 16, a metering pump manufactured by Iwaki Co., whose pump head is made of Teflon, was used.

In order to manufacture an optical disk by the optical disk manufacturing apparatus as described above, first, the drive section 3 connected to the control section 21 rotates the holding section 2 to rotate the optical disk substrate 1 in a predetermined direction at a low speed. . When forming the protective film, the optical disk substrate 1 is placed on the holding portion 2 with the recording portion side facing upward, and when forming the antistatic protective film, the optical disk substrate 1 is placed on the transparent substrate side. It is placed on the holding unit 2 with the upper side. Further, in the optical disk manufacturing apparatus as described above, a magneto-optical disk can be manufactured by using a magneto-optical disk substrate in which a recording portion having a recording magnetic film is formed on a transparent substrate instead of the optical disk substrate 1. .

Then, in this state, a predetermined amount of the ultraviolet curable resin 4 in the supply tank 5 is sucked up into the pipe 6 by the first pump 20 and filtered by the first filter 8 arranged in the middle of the pipe 6. After that, the resin is supplied onto the optical disk substrate 1 from the resin supply port 7.

Next, the control unit 21 is adjusted to adjust the drive unit 3, and the rotation of the holding unit 2 is increased to rotate the optical disc substrate 1 at a high speed. Then, the ultraviolet curable resin 4 on the optical disc substrate 1 is spread over the entire surface of the optical disc substrate 1, and a coating film of the ultraviolet curable resin 4 is formed on the entire surface of the optical disc substrate 1.

At this time, the surplus portion of the ultraviolet curable resin 4 supplied to the optical disc substrate 1 is shaken off by the rotation of the optical disc substrate 1 and scattered from the optical disc substrate 1. The surplus ultraviolet curable resin 4 is used as the resin tray 1
0 from the hole 11 of the resin tray 10 to the pipe 12
Through the recovery tank 13.

When an optical disk is manufactured by the optical disk manufacturing apparatus of this embodiment, the amount of the ultraviolet curable resin 4 in the supply tank 5 decreases. However, in the optical disk manufacturing apparatus of the present embodiment, the weight of the ultraviolet curable resin 4 in the supply tank 5 is managed by the load cell 19a, and when the amount of the ultraviolet curable resin 4 in the supply tank 5 decreases to some extent, The second pump 16 sucks up the ultraviolet curable resin 4 in the recovery tank 13 through the pipe 15a. Then, the ultraviolet curable resin 4 filtered by the second filter 17 is supplied until the ultraviolet curable resin 4 in the supply tank 5 reaches a constant amount.

When the optical disk manufacturing apparatus of this embodiment further manufactures an optical disk, the amount of the ultraviolet curable resin 4 in the recovery tank 13 also decreases. However, in the optical disk manufacturing apparatus of the present embodiment, the weight of the ultraviolet curable resin 4 in the recovery tank 13 is also controlled by the load cell 19b, and when the amount of the ultraviolet curable resin 4 in the recovery tank 13 decreases to some extent, By switching a three-way valve (not shown), the second pump 16 sucks up the ultraviolet curable resin 4 in the new liquid tank 14 through the pipe 15b. Then, the ultraviolet curable resin 4 filtered by the second filter 17 is supplied until the ultraviolet curable resin 4 in the supply tank 5 reaches a constant amount.

If the optical disk manufacturing apparatus of this embodiment continues to manufacture optical disks, the ultraviolet curable resin 4 in the new liquid tank 14 will be exhausted. However, in the optical disk manufacturing apparatus of this embodiment, since the weight of the ultraviolet curable resin 4 in the new liquid tank 14 is controlled by the load cell 19c, it is easy to know when to replace the new liquid tank 14.

That is, in the optical disk manufacturing apparatus of this embodiment, when the ultraviolet curable resin 4 is first supplied to the supply tank 5 and the new liquid tank 14 and the apparatus is operated, the ultraviolet curable resin is automatically generated. It is possible to manufacture an optical disc while reusing it, and it is possible to reduce the manufacturing cost and improve the productivity.

Further, by using the optical disk manufacturing apparatus of this embodiment, it is possible to reduce the amount of waste liquid generated during manufacturing, which contributes to the protection of the global environment.

In the optical disk manufacturing apparatus of this embodiment, the UV curable resin 4 to be reused is used after being filtered by the second filter 17 to remove impurities such as dust. It does not deteriorate the characteristics of.

Further, in the optical disk manufacturing apparatus of this embodiment, the first pump 20 is a diaphragm pump and a control unit (not shown) is connected to the optical disk manufacturing apparatus. Curable resin 4
Are supplied onto the optical disk substrate 1 to manufacture an optical disk having good characteristics.

In the above-described conventional magneto-optical disk manufacturing apparatus, the ultraviolet curable resin is conveyed by the pressure feeding method in which pressure is applied, and the supply tank when the ultraviolet curable resin in the supply tank is reduced When replacing the device, it is necessary to stop the device, release the pressure, and apply the pressure again when the device is operating, which causes a problem that the operating rate of the device is reduced. Further, if the supply tank is frequently replaced, the workability is poor, and the periphery of the device is contaminated.

Furthermore, even if the ultraviolet curing resin once used in the conventional magneto-optical disk manufacturing apparatus is recovered and reused, when the ultraviolet curing resin to be reused is moved to the supply tank. It is necessary to stop the device, release the pressure to perform the work, and apply the pressure again when the device is in operation, which reduces the operation rate of the device.

However, in the optical disk manufacturing apparatus of this embodiment, since the optical disk is manufactured while automatically reusing the ultraviolet-curing resin, the frequency of replacement of the new liquid tank is low, and the workability is good, and The area around the device is less likely to get dirty.

Further, in the optical disk manufacturing apparatus of this embodiment, the ultraviolet curable resin is conveyed by the diaphragm pump, and it is not necessary to apply pressure to the supply tank, the recovery tank and the new liquid tank, and the new liquid tank There is no need to apply pressure after the device is stopped when replacing the device, and the operating rate of the device is improved.

Furthermore, in the optical disk manufacturing apparatus of this embodiment, it is needless to say that there is no need to stop the apparatus when the reusable UV-curable resin recovered in the recovery tank is conveyed to the supply tank. Improves the operating rate of.

Next, changes in the quality of the ultraviolet curable resin when the optical disk manufacturing apparatus of this embodiment was used were investigated. That is, 20 kg of each of the three kinds of UV-curable resins A, B, and C are circulated in the optical disk manufacturing apparatus of this embodiment, and the viscosity, water content, refractive index, impurity ion concentration, and curing performance of these UV-curable resins are circulated. , Coating properties were investigated. As a result, the viscosity and the water content were changed, but the other properties were not changed. The results of viscosity and water content are shown in Table 1. The UV-curable resin C is suitable for forming an antistatic protective film provided to prevent damage to the substrate or to prevent static electricity.

[0050]

[Table 1]

Subsequently, an optical disk having a protective film formed by coating a new UV curable resin of A, B and C and a resin which has been circulated for 2 weeks is manufactured, and these optical disks of 80 ° C. and 85 RH% are manufactured. The deterioration of the error rate after storage in the atmosphere was investigated. As a result, the rate of deterioration of the error rate is the same between the optical disc coated with a new one of the same UV curable resin and the one that has been circulated for two weeks, and the UV curable resin circulates, in other words, reused. It was confirmed that the curable resin did not deteriorate and the characteristics of the protective film did not deteriorate.

With respect to the optical disk using the UV-curable resin of C, since the UV-curable resin is used for forming an antistatic protective film provided for preventing static electricity, the change in surface resistance is also measured. However, the degree of deterioration of the surface resistance does not change between the optical disc using the new one and the optical disc using the one that has been circulated for two weeks, and the ultraviolet curing resin is circulated, in other words, reused to cure the ultraviolet rays. It was confirmed that the mold resin did not deteriorate, and thus the characteristics of the protective film did not deteriorate.

That is, when an optical disk is manufactured by the optical disk manufacturing apparatus of this embodiment, the viscosity and the water content of the ultraviolet curable resin to be used are controlled, and if the entire exchange is performed within a certain period, the ultraviolet curable resin is cured. It was confirmed that the characteristics of the protective film did not deteriorate even when the optical disk was manufactured while the mold resin was reused, and the characteristics of the manufactured optical disk were stable.

[0054]

As is apparent from the above description, the present invention provides a method for manufacturing an optical disk, which comprises applying a UV-curable resin by a spin coating method to form a protective film.
Since the ultraviolet curable resin shaken off by the rotation is collected and reused through the filter, the manufacturing cost is reduced and the productivity is improved. Further, according to the present invention, it is possible to reduce the amount of waste liquid generated at the time of production, which can contribute to global environment protection.

At this time, the ultraviolet curable resin is reused after being filtered by a filter to remove impurities such as dust, and thus does not deteriorate the characteristics of the manufactured optical disc.

[Brief description of drawings]

FIG. 1 is a schematic view of an essential part showing an optical disk manufacturing apparatus to which the present invention is applied.

FIG. 2 is a sectional view schematically showing the structure of a magneto-optical disk.

FIG. 3 is a schematic diagram showing the principle of the spin coating method.

FIG. 4 is a schematic view of a main part of a conventional magneto-optical disk manufacturing apparatus.

[Explanation of symbols]

 1 Optical Disc Substrate 4 Ultraviolet Curing Resin 5 Supply Tank 7 Resin Supply Port 10 Resin Receptacle 13 Recovery Tank 17 Second Filter

Claims (4)

[Claims] 1. A method of manufacturing an optical disc, wherein a UV-curable resin is applied by spin coating to form a protective film, wherein the UV-curable resin shaken off is collected and reused through a filter. Optical disc manufacturing method. 2. The method of manufacturing an optical disc according to claim 1, wherein the protective film is a protective film formed on the recording film or the reflective film. 3. The method of manufacturing an optical disc according to claim 1, wherein the protective film is an antistatic protective film formed on the laser light irradiation surface of the optical disc substrate. 4. The method of manufacturing an optical disk according to claim 1, wherein the optical disk is a magneto-optical disk.