JP2757520B2 - Optical disc manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an optical disk such as a digital audio disk (so-called compact disk) and a magneto-optical disk. Transfer the concavo-convex pattern on the substrate,
The present invention relates to an improvement in a method of manufacturing an optical disk by a so-called 2P method (photopolymerization method).

[Summary of the Invention]

The present invention provides high productivity and precise transfer by regulating the viscosity of the UV curable resin at the time of screen printing when transferring the concavo-convex pattern of the stamper by photopolymerization of the UV curable resin screen-printed on the disk substrate. It achieves performance.

[Conventional technology]

When manufacturing optical discs such as digital audio discs (so-called compact discs) and magneto-optical discs, an uneven pattern is formed on a liquid ultraviolet curable resin as a method of transferring uneven patterns such as pits and grooves (guide grooves) onto a substrate. A so-called 2P method has been proposed, in which the stamper is brought into close contact and the ultraviolet curable resin is photopolymerized by ultraviolet irradiation.

In the 2P method, for example, a liquid UV-curable resin is applied to the substrate surface of a disk substrate having optical transparency by screen printing, and a stamper having an uneven pattern formed on the surface of the UV-curable resin is brought into close contact with a roller or the like. By irradiating ultraviolet rays from the substrate side, the ultraviolet curable resin is photopolymerized and cured, and the disk substrate is peeled off from the stamper together with the ultraviolet curable resin, thereby forming a fine uneven pattern (pits and grooves) on the surface of the stamper. This is a method of transferring to a surface.

According to the 2P method, since the ultraviolet curable resin is brought into close contact with the stamper in a liquid state, it has an advantage that the fidelity of replication is excellent and the stamper is hardly deteriorated, especially when a glass substrate is used as a disk substrate. It is also very advantageous in terms of dimensional stability, heat resistance, birefringence and the like.

[Problems to be solved by the invention]

By the way, when transferring a concavo-convex pattern to a disk substrate by the 2P method, the viscosity of the ultraviolet curable resin at the time of screen printing greatly affects the transfer performance.

Until now, it has been considered that the lower the viscosity is, the more advantageous it is to improve the transfer performance, and the viscosity of the ultraviolet curable resin at the time of screen printing is set to about several hundred cps.

However, if the viscosity of the ultraviolet curable resin is too low, the resin tends to protrude to the outer periphery of the substrate, and the resin remains on the stamper, which hinders the next transfer step. The extruded resin must be removed each time, and the productivity is greatly reduced. Also, if the viscosity of the ultraviolet curable resin is too low, for example, the resin flows during the transfer from the pressure bonding step with a roll to the ultraviolet irradiation step,
On the contrary, there is a problem that the transfer performance is deteriorated.

In view of the above, the present invention has been proposed in view of the above-described conventional circumstances, and has no protrusion or flow of an ultraviolet curable resin, and is capable of faithfully transferring the pattern of the concave and convex of the stamper, and with high productivity. It is an object of the present invention to provide a method for producing the same.

[Means for solving the problem]

In order to achieve the above object, the present invention is to apply an ultraviolet curable resin on a substrate surface of a disk substrate in a predetermined pattern by screen printing, and then closely contact a stamper having an uneven pattern formed on the ultraviolet curable resin. A method for manufacturing an optical disc, which irradiates ultraviolet rays and cures by photopolymerization to transfer a concave / convex pattern of a stamper, is characterized in that the viscosity of the ultraviolet curing resin at the time of screen printing is 2500 to 6000 cps.

[Action]

When screen-printing an ultraviolet-curable resin, if the viscosity of the ultraviolet-curable resin is too high, a uniform transfer layer is not formed, and transferability is greatly deteriorated.

Conversely, if the viscosity of the ultraviolet curable resin is too low, the resin will run out or flow.

On the other hand, in the present invention, the viscosity of the ultraviolet curable resin at the time of screen printing is optimized at 2500 to 6000 cps, and the transfer layer is formed stably with a uniform thickness. Further, shape deterioration due to the flow of the resin is also eliminated.

〔Example〕

Hereinafter, a specific example of a method of manufacturing an optical disk to which the present invention is applied will be described in detail.

In this example, a glass substrate was used as the disk substrate.

In order to produce an optical disk, it is necessary to perform a 2P process on a glass substrate that has been surface-treated with a coupling agent such as a silane coupling agent, and transfer the concavo-convex pattern of the stamper.

FIG. 1 shows a schematic configuration of an example of an apparatus for manufacturing an optical disk by the 2P method.

This manufacturing apparatus continuously processes a series of processes of the 2P method, and includes a substrate supply unit (1) that accommodates a glass substrate that has been subjected to a surface treatment with the coupling agent,
A screen printing (2) for applying an ultraviolet curable resin to the glass substrate, a transfer unit (3) for photo-polymerizing the roll by pressing a stamper on the ultraviolet curable resin, and irradiating ultraviolet rays, and a glass substrate on which a concavo-convex pattern is transferred Substrate carrying-out sections (4) to be accommodated are sequentially arranged on a machine base (5).

The substrate supply section (1) is for temporarily stocking the glass substrate (6) in order to supply the glass substrate (6) one after another to the screen printing section (2) arranged adjacently. And a multi-stage cartridge (7) for accommodating a plurality of glass substrates (6).

The screen printing section (2) includes a printing table (8) having a substrate mounting section for securely holding the glass substrate (6) by vacuum chucking, a screen for screen printing, a squeegee, and the like. A liquid ultraviolet curing resin (9) is screened on one surface of a glass substrate (6) mechanically taken out one by one from a cartridge (7) by a first substrate delivery mechanism (not shown). It is applied by printing.

The transfer unit (3) includes a stamper (10) having a concave / convex pattern formed by inverting pits or grooves on the surface, and a stamper holder (11) holding the stamper (10) and movable in the front-rear direction. A roller (12) for pressing the glass substrate (6) coated with the ultraviolet curable resin (9) and the stamper (10) along a moving direction of the stamper holder (11); A light source (13) for irradiating ultraviolet rays for curing the cured resin (9) is provided.

In addition, between the screen printing part (2) and the transfer part (3), the glass substrate (6) on the printing table (8) is turned upside down, and the surface coated with the ultraviolet curable resin (9) has a surface. A second substrate delivery mechanism for transferring the glass substrate (6) to the transfer section (3) is provided so as to face the stamper (10), but is not shown here.

The substrate unloading section (4) includes a multi-stage unloading cartridge (14), similarly to the substrate supply section (1).
The glass substrate (6) peeled off from the stamper (10) after the transfer of the concavo-convex pattern of the stamper (10) in the transfer part (3) is sequentially accommodated in the glass substrate (6) by the third substrate delivery mechanism. ing. The third substrate delivery mechanism includes a rotary arm (16) that is rotated around a rotary shaft (15), and a suction head (17) provided at the tip of the rotary arm (16). And has a function of sucking the glass substrate (6) to the suction head (17) and transferring the glass substrate (6) from the transfer section (3) to the unloading cartridge (14) of the substrate unloading section (4).

In the optical disk manufacturing apparatus having the above configuration,
An optical disk substrate is produced through the following steps.

That is, the glass substrate (6) that has been subjected to the heat treatment or the surface treatment with the coupling agent is first supplied to the substrate supply unit (1)
Is stored in the cartridge (7).

Then, it is transferred to the printing table (8) of the screen printing unit (2) by a first substrate transfer mechanism (not shown).

The glass substrate (6) on the printing table (8) is immediately coated with an ultraviolet curable resin (9) by a screen printing tool as shown in FIG. 2A.

The screen printing tool includes a printing screen (1) made of a thin stainless steel plate on which a predetermined opening pattern is formed.
8) and squeegee (19) as main components,
After the ultraviolet curable resin (9) is supplied onto the printing screen (18) stretched over the frame pair (20), the ultraviolet curable resin (9) is swept by the squeegee (19), so that the glass substrate ( 6) UV curable resin (9) is printed on the surface according to the opening pattern.

In this example, the opening pattern of the printing screen (18) is a turtle shell pattern (18a) assembled in a crescent shape,
The stamper (10) is composed of a circular pattern (18b) that is distributed and arranged on the crescent-shaped tortoiseshell pattern side.
This prevents leakage of the ultraviolet curable resin and generation of bubbles at the time of pressure bonding.

The printing screen (18) will be described in further detail. As shown in FIG. 3, when the running direction of the roll (12) with respect to the glass substrate (6) is set to the direction of arrow A, the printing screen (18) is used. )) (A region corresponding to the glass substrate (6) on the pressure start end side by the roller (12) when the glass substrate (6) is pressed against the stamper (10)). A tortoiseshell pattern (18a) is provided in a crescent shape at a position along the outer peripheral edge of the glass substrate (6). Further, the first circular pattern (18b ₁ ) and the second circular pattern (18b ₂ ) having a smaller diameter are formed along the crescent shape so as to avoid the area around the center hole of the glass substrate (6). Has been drilled. In the semicircular region on the pressure end end side, a fine resin replenishment pattern (18c) is arranged in an arc along the center hole of the glass substrate (6), and the resin replenishment pattern (18c) is formed. ), The first circular pattern (18b ₁ ) and the second circular pattern (18b ₂ ) are arranged continuously in an arc shape avoiding the outer peripheral edge of the substrate (6) so as to double surround the outer peripheral side of the substrate (6). .

Printing screen having opening pattern as described above (18)
By using, the UV curable resin (9) can be printed stably by preventing the screen (18) from being distorted, and the UV curable resin (9) when pressed by the roller (12) can be used. Leakage can be prevented beforehand.

On the other hand, the ultraviolet curable resin (9) supplied onto the printing screen (18) is, for example, an acrylate compound or a polythiol compound mainly composed of a monomer or oligomer of mono-, di- or triester of acrylic acid or methacrylic acid. , A polyene compound, and the like, and a photopolymerization initiator, a photopolymerization accelerator, an antioxidant, and the like are added as necessary. Of course, the present invention is not limited to this, and any ordinary ultraviolet curable resin can be used.

At this stage, the ultraviolet curable resin (9) has not been cured by photopolymerization, and therefore exhibits a liquid state.
At this time, the viscosity of the ultraviolet curing resin (9) is 2500 to 6000.
Must be cps.

The viscosity of the UV curable resin (9) during screen printing
If it is less than 2500 cps, the resin (9) tends to protrude from the outer peripheral portion of the glass substrate (6), and the resin (9) may remain on the stamper (10) in a transfer step described later. Further, even when the resin (9) is brought into close contact with the stamper (10) by pressure bonding by the roller (12), the resin (9) flows during the transfer to the light source (13), and the transfer shape may be deteriorated. Conversely, if the viscosity of the UV-curable resin (9) exceeds 6000 cps, the resin (9) may not be sufficiently stretched even when pressed with the roller (12), and a uniform film may not be formed. In addition, the resin (9) does not sufficiently penetrate into the concave / convex pattern of the stamper (10), resulting in poor transferability.

The viscosity of the ultraviolet curable resin (9) specified here is the viscosity from screen printing to before the irradiation of the ultraviolet light by the light source (13). Therefore, the viscosity at the temperature at which these steps are performed is within the above range. I just need. Usually, these steps are performed at room temperature, so that the viscosity at 25 ° C. may be within the above range.

Methods for adjusting the viscosity of the ultraviolet-curable resin (9) to the above-mentioned range include a method of changing the degree of polymerization of the oligomer, a method of changing the ratio of a linear monomer to a branched monomer, and a method of adjusting the monomer constituting the resin. Examples include a method of introducing a side chain.

FIG. 2B shows a glass substrate (6) on which an ultraviolet curable resin (9) is screen-printed by the above-described method.

Next, the glass substrate (6) is transferred to the transfer section (3), and the concavo-convex pattern of the stamper (10) is transferred.

When the glass substrate (6) is transferred to the transfer section (3), the glass substrate (6) is turned upside down so that the surface on which the ultraviolet curable resin (9) is applied is on the lower side as shown in FIG. 2C. Then, it is superimposed on the stamper (10) on the stamper holder (11).

Next, the glass substrate (6) superimposed on the stamper (10) is pressed by a roller (12) as shown in FIG. 2D by moving the stamper holder (11), and the ultraviolet curable resin (9) Between the stamper (10). At this stage, since the ultraviolet curable resin (9) is in a liquid state and has an appropriate viscosity as described above, it enters uniformly into the fine uneven pattern of the stamper (10) without gaps. In addition, it does not protrude from the glass substrate (6) and remains on the stamper (10).

Thereafter, the stamper holder (11) further moves, and the glass substrate (6) in close contact with the stamper (10) is transported below the light source (13).

Then, as shown in FIG. 2E, ultraviolet rays are irradiated from the glass substrate (6) side, and the glass substrate (6) and the stamper (10) are irradiated.
The ultraviolet curable resin (9) filled in between is cured by photopolymerization. Thus, the concavo-convex pattern on the surface of the stamper (10) has been transferred to the ultraviolet curable resin layer on the glass substrate (6).

After the transfer of the concavo-convex pattern, the glass substrate (6) is peeled off from the stamper (10) as shown in FIG.
Is transferred to the substrate unloading section (5) by the substrate delivery mechanism.

The disk substrate on which the concave / convex pattern of the stamper (10) has been transferred by the above-described optical disk manufacturing apparatus is converted into an optical disk by further forming a reflective film or a recording film, or providing a protective layer or the like. Is optional, so that a reflective film, a recording film,
The protective film and the like can be arbitrarily selected according to the application.

For example, a digital audio disc or a so-called CD
-In a ROM or the like, a metal reflection film of Al or the like is formed on a disk substrate on which a concavo-convex pattern is transferred. For magneto-optical disks, magneto-optical properties (Kerr effect and Faraday effect)
A perpendicular magnetization film (for example, TbFeCo or the like) having the following is formed.
In addition, the present invention can also be applied to an optical disc having a recording layer of a low melting point metal thin film, a phase change film, a film containing an organic dye, or the like.

The optical disc substrate manufactured through the above steps has excellent transferability of the concave and convex pattern of the stamper (10), and has high reliability without formation and deterioration of pits and grooves. Also, because a glass substrate is used,
It also exhibits excellent properties in terms of dimensional stability, heat resistance, birefringence, etc.

As described above, the embodiment to which the present invention is applied has been described.
The present invention is not limited to this embodiment. For example, the material of the disk substrate, the type of the ultraviolet curable resin, the shape of the opening pattern of the printing screen, and the like are arbitrary.

〔The invention's effect〕

As is clear from the above description, in the present invention, since the viscosity of the ultraviolet curable resin at the time of screen printing is made appropriate, it is possible to prevent the resin from protruding from the substrate and secure high productivity. can do.

Further, within the viscosity range of the ultraviolet-curable resin in the present invention, the ultraviolet-curable resin can be sufficiently filled in the stamper, the shape deterioration due to the flow of the resin can be suppressed, and the precise transfer performance can be realized. It is possible.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an example of a disk manufacturing apparatus for transferring an uneven pattern of a stamper. 2A to 2F are schematic perspective views for explaining the process of the 2P method. FIG. 2A is a screen printing step, FIG. 2B is a glass substrate on which an ultraviolet curable resin is printed, and FIG. 2C is a process of superimposing on a stamper, FIG. 2D
Fig. 2E is an ultraviolet irradiation step,
FIG. 2F shows a step of peeling from the stamper. FIG. 3 is a plan view showing an example of an opening pattern provided on a printing screen. 6 Glass substrate 9 UV curable resin 10 Stamper

Claims (1)

(57) [Claims] An ultraviolet curable resin is applied on a substrate surface of a disk substrate in a predetermined pattern by screen printing, and then a stamper having a concavo-convex pattern is adhered to the ultraviolet curable resin and irradiated with ultraviolet light. In a method of manufacturing an optical disk for curing and transferring a concave / convex pattern of a stamper, the viscosity of the ultraviolet curable resin at the time of screen printing is set to 2500 to 60.
A method for manufacturing an optical disk, wherein the method is set to 00 cps.