JP2003033713A - Hardened film formed body, hardended film forming method and hardened film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a liquid resin hardened film in an even thickness on the surface of a disc substrate. SOLUTION: The disc substrate 1 is formed by sequentially superimposing a visible radiation reflecting layer 21, a primary dielectric layer 22A, a phase changing layer 23, a secondary dielectric layer 22B on a substrate 20. A translucent hardened film 24 is formed on the top surface. When the film 24 is formed, the disc substrate 1 is heated by performing irradiation with a flash irradiation device via a luminous energy controlling member. A temperature distribution is formed so as to allow a temperature rise on the center side of a disc substrate surface to be smaller and that toward the peripheral side of the substrate to be larger by allowing the luminous energy controlling member to be permeated thereinto. The viscosity of an ultraviolet curative composition S becomes smaller on the periphery of the disc substrate at a high temperature to obtain an even thickness of the composition by circularly applying and flattening the ultraviolet thermosetting composition S on the surface of the disc substrate. The film 24 of even thickness is formed by irradiating ultraviolet rays onto the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cured film forming body obtained by applying a liquid resin to the surface of an information recording layer or the like provided on a base material such as a disk or a disk substrate having an information recording layer and curing the resin. The present invention relates to a cured film forming method and a cured film forming apparatus.

[0002]

2. Description of the Related Art Examples of base materials of this type include CD (compact disc), MO (magneto-optical disc), and PD.
(Phase change optical disk), DV-R called a next-generation high recording density medium, DVD (digital versatile disk), and the like. Conventionally, spin coating has been used as a method for forming a cured film of an ultraviolet curable resin composition, which is a liquid resin, on the surface of an information disc or an information disc substrate (hereinafter referred to as a disc substrate) that constitutes this type of base material. Many laws have been adopted. The main reason for providing the cured film is to protect the information recording layer. As the ultraviolet curable resin composition used here, there is usually a fast-acting radical-polymerization type ultraviolet curable resin composition which is instantly cured by irradiation with ultraviolet rays. An example of a technique for covering and protecting the information recording layer of the substrate with such a cured film will be described with reference to FIG. FIG. 4 is a diagram showing a process of forming a cured film on a substrate by a spin coating method.

First, as shown in FIG. 4A, the information recording layer 1
While the disc substrate 1 is rotated along the central axis C of the disc substrate 1 on which 00 is provided, the ultraviolet curable resin composition S is uniformly arranged in an annular shape by the coating device 5. The position where the ultraviolet curable resin composition S is arranged is the disk substrate 1
The viscosity of the ultraviolet curable resin composition S depends on the thickness of the cured film to be formed, but usually 10
The thing of about 0-2500 mPa.s is used. Next, as shown in FIG. 4B, when the disk substrate 1 is rotated about the central axis C at a speed of 1000 to 4000 rotations per minute for 1 to 3 seconds, the inner surface of the disk substrate 1 is coated. The ultraviolet curable resin composition S is uniformly spread and spread over the entire surface of the disk substrate by the centrifugal force of rotation.
As a result, a coating layer 101 covering the information recording layer 100 as shown in FIG. 4C is formed. The thickness of the coating layer 101 varies depending on the viscosity of the ultraviolet curable resin composition S, the speed at which the disk substrate 1 is rotated, the time for rotation, and the like. Generally, the smaller the viscosity of the ultraviolet curable resin composition S, the higher the rotation speed of the disk substrate 1, and the longer the rotation time, the thinner the coating layer 101 becomes. When the liquid coating layer 101 formed as described above is irradiated with ultraviolet rays from above the coating layer 101, the coating layer 101 is instantly cured to form a cured film 101, and thus the cured film 101 is formed. Complete. Although depending on the type of the ultraviolet curable resin composition S, when the coating layer 101 is changed to the cured film 101, usually 5 to 15% of curing shrinkage occurs, and the thickness decreases accordingly.

[0004]

By the way, the cured film 101 formed as described above has one characteristic tendency. That is, the thickness distribution of the hardened film 101 is substantially uniform in the circumferential direction, but tends to increase in thickness from the inner side to the outer side in the radial direction. The reason for this is considered to be a phenomenon that occurs because the liquid ultraviolet curable resin composition S on the inner peripheral side is pushed to the outer peripheral side by centrifugal force and deposited. Such a cured film 1
The thickness variation of 01 in the radial direction is not preferable in terms of reliability and quality of the disc. Particularly in the case of DV-R, which is regarded as a next-generation high recording density disc, the range of variation is strictly limited to ± 3 μm with respect to the average thickness of 100 μm, and such a cured film 101 is stabilized by the conventional spin coating method. Was very difficult to form.

The present invention has been made in view of the above circumstances, and a cured film formed by curing a liquid resin is formed on the entire surface of a substrate so as to have a uniform thickness. An object is to provide a film forming body, a cured film forming method, and a cured film forming apparatus.

[0006]

A cured film forming body according to the present invention forms a surface of a base material in a predetermined temperature distribution state and applies a liquid resin uniformly on the surface of the base material. Is cured to form a cured film. The liquid resin in the present invention, for example, the ultraviolet curable resin composition has a tendency that the viscosity exponentially and rapidly changes with respect to the temperature change. Therefore, during the spreading process such as rotary spreading, it has a characteristic that it is easily spread and thin in a low viscosity part, and it is hard to spread in a high viscosity part and the thickness is thick. Changes. It is preferable to control the film thickness of the liquid resin obtained by utilizing the properties of the liquid resin by temperature. That is, corresponding to the thickness distribution of the liquid resin when the temperature distribution is made uniform, the temperature of the thicker portion (outer peripheral side) is increased and the temperature increase of the thinner portion (inner peripheral side) is suppressed. By setting the temperature distribution to change in this way, it is possible to control the thickness of the liquid resin to be uniform.

The method for forming a cured film according to the present invention comprises a step of applying a liquid resin in an annular shape on at least the inner peripheral portion of the surface of the base material, and a uniform application by rotating the applied liquid resin together with the base material. A method for forming a cured film, which comprises a step of spreading and hardening a liquid resin spread on the surface of a base material, and forms the surface of the base material in a predetermined temperature distribution state. And a temperature distribution forming step is provided. With the surface of the substrate formed in a predetermined temperature distribution state, the liquid resin is applied in an annular shape, or the liquid resin previously applied in an annular shape is uniformly spread by the rotation of the base material. The thickness of the liquid resin can be uniformly controlled over the entire surface of the substrate by suppressing the liquid resin from being pushed and deposited on the outer peripheral side during spreading.

The liquid resin may be an ultraviolet curable resin composition. When the present invention is applied to an optical disc manufacturing process or the like, it is preferable to use, as the liquid resin, an ultraviolet curable resin composition having an excellent function of protecting the information recording layer and the like. The temperature distribution is preferably formed before the end of the coating process or at any timing during the spreading process. It is preferable that the temperature distribution is formed before the step of applying the liquid resin. It is preferable to carry out the spreading treatment before the rearrangement of the temperature distribution once formed occurs by heat conduction or radiation. If the temperature distribution is formed in such a process, the liquid resin is spread to a uniform thickness even by the rotary spreading, and the processing efficiency is high. A temperature distribution may be formed during the spreading process. If the temperature distribution is formed during such a process, the liquid resin to be spread is easily spread to a uniform thickness and the processing efficiency is relatively high. On the other hand, if the liquid resin is moved by performing the temperature distribution processing after the spreading processing is completed, reflow due to the temperature distribution formation occurs in the liquid resin once applied, and the resin thickness is rearranged. There is a drawback that it takes time and processing takes time.

When forming the temperature distribution, the temperature of the surface of the base material is uniform in the circumferential direction of the same radius, but a predetermined temperature gradient may be provided in the radial direction. If the temperature is uniform, the liquid resin is set by the spreading process so that the thickness gradually increases from the inner circumference side to the outer circumference side.In this case, the temperature gradient gradually increases from the inner circumference side to the outer circumference side. If the rise is set to be large, it is possible to control the liquid resin thickness to have a uniform thickness as a whole. When setting the temperature gradient, it is preferable that the magnitude of the gradient is appropriately adjusted according to the viscosity of the liquid resin used and the environmental temperature, and the range in which the set temperature gradient does not adversely affect the shape of the disk. It is preferable to adjust Also,
The temperature distribution may be formed by bringing a high temperature object having a predetermined surface temperature into contact with or close to the base material. By bringing a high-temperature object that has been subjected to high-temperature heat treatment into contact with or close to the base material, heat can be conducted to the surface of the base material, and the temperature distribution can be reliably formed. The temperature distribution may be formed by irradiation with light including infrared rays. In this case, it is preferable to irradiate the base material with a light ray containing a large amount of infrared rays (heat rays) from the viewpoint of irradiation efficiency, and at that time, the light irradiation amount needs to be adjusted so that the base material is not thermally deformed by the light irradiation. . Light irradiation is flashing 1
It may be performed once or twice or more.
The irradiation energy per time, the peak intensity of the light intensity, the pulse width, the repetition rate, etc. are adjusted so that the information recording layer of the base material is not damaged or thermally affected by the light irradiation.
Flash light irradiation may be repeated until a predetermined temperature distribution is formed.

The cured film forming apparatus according to the present invention is a cured film forming apparatus in which a liquid resin is coated on a base material and cured, and the liquid resin is formed into an annular shape at least on the inner peripheral portion of the surface of the base material. A coating means for coating, a spreading means for uniformly spreading the applied liquid resin by rotating the coated liquid resin together with a base material, and a temperature distribution forming means for forming a surface of the base material in a predetermined temperature distribution state. It is characterized by being provided. Before the liquid resin spreading process is completed, the surface of the base material should be formed in a predetermined temperature distribution state, and the liquid resin should be applied to the surface of the base material in an annular shape and spread uniformly. In this case, the thickness of the liquid resin can be uniformly controlled over the entire surface of the base material although the liquid resin is likely to be deposited on the outer peripheral side due to the centrifugal force. As the temperature distribution forming means, a means for conducting heat mainly by contact, a radiating means utilizing thermal radiation, etc. can be adopted.

The temperature distribution forming means may be provided with a light source and a light amount adjusting member for adjusting the amount of light emitted from the light source to the substrate. By irradiating the substrate with light through the light amount adjusting member, the amount of light irradiated on the surface of the substrate can be adjusted depending on the position, and the temperature distribution can be appropriately formed. It is preferable that the light amount adjusting member is provided on the optical path between the light source and the base material to be the irradiated body. It is preferable that the light amount adjusting member is made of a material having high heat resistance and provided so that the areas of the plurality of light transmitting portions change corresponding to the surface of the disk substrate. The change of the area of the light transmitting portion is preferably determined in consideration of the illuminance distribution on the surface of the base material by the light source and the target predetermined temperature distribution. Alternatively, it may be carried out so that a predetermined temperature distribution can be obtained by arranging a known and commonly used optical filter means. The light source may be a flash light irradiation device that flashes light rays including infrared rays. A temperature distribution can be suitably formed by setting the amount of heat or irradiation amount obtained on the surface of the base material by the flash light irradiation or the flash repetition rate (interval) to such an extent that the base material is not deformed. The arrangement of the flashlight irradiation device is preferably adjusted in shape and number so that a predetermined temperature distribution can be obtained. Further, it is preferable to use a flash light irradiation means capable of varying irradiation energy, peak intensity, pulse width, repetition rate, etc. per time.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to DV-
The production of R will be described as an example. It should be noted that the same members and the like as those in the above-described conventional technique will be described using the same reference numerals. First, Fig. 1 is D
It is a longitudinal cross-sectional view showing a schematic structure of a V-R information recording disk. In FIG. 1, a disc substrate 1 of a DV-R information recording disc has a substrate 20 made of a plastic such as polycarbonate and having an outer diameter of 12
The thickness is 0 mm and the thickness is 1.1 mm. A visible light reflection layer 21 is provided in a concentric ring shape on the surface 20a of the substrate 20, and a ring-shaped first dielectric layer 22A, a phase change layer 23 for recording information, and a second ring are formed on the upper surface thereof. The disk substrate 1 is configured by sequentially stacking the dielectric layers 22B. Then, on the uppermost surface of the disk substrate 1, a transparent cured film 24 obtained by curing, for example, a radical polymerization type ultraviolet curable resin composition as the ultraviolet curable resin composition S which is a liquid resin is formed as a coating layer. . The cured film 24 includes not only the second dielectric layer 22B but also the layers 21, 22A, 23,
The second dielectric layer 22 is formed so as to cover the inner and outer surfaces of 22B and has a thickness of, for example, 0.1 mm and has a substantially circular shape.
It is uniform over the entire surface of B. In addition, the visible light reflection layer 2
A disk center hole 25 having a diameter of, for example, 15 mm is formed through the center of the substrate 20 where the ring-shaped laminated portion from 1 to the cured film 24 is not provided. In such a disc substrate 1, a cured film 2 is used for recording and reading information.
It is performed from the 4 side.

Next, the DV-R disk substrate 1 according to the embodiment has a thickness of 0.1 mm on the information reading surface side.
A cured film forming apparatus for forming the cured film 24 composed of the ultraviolet curable resin composition S will be described with reference to FIGS. 2 and 3. FIG. 2 is a plan view showing a schematic configuration of a cured film forming apparatus, FIG. 3A is an explanatory view showing a temperature distribution forming means used in the cured film forming apparatus, and FIGS. It is a top view of a member. The cured film forming apparatus 30 shown in FIG. 2 is roughly composed of a disc substrate supply unit R1, a disc substrate preparation unit R2, a disc substrate inspection unit R3, and a disc substrate storage unit R4, all of which are inside a casing (not shown). It is stored in. The disk substrate supply unit R1
A disk substrate storage device ST1 in which six disk holders 11 in which a plurality of disk substrates 1 without the hardened film 24 are laminated are arranged and stored in an annular shape at predetermined intervals.
And a transfer device 2 that takes out the disc substrates 1 one by one from the uppermost layer of the disc holder 11 that has moved to the disc substrate taking-out position A1 and feeds the disc substrates 1 to the disc making section R2. The disc substrate storage device ST1 is configured to be rotatable in the direction of the arrow shown in the figure, and when the disc substrate 1 stacked on the disc holder 11 at the disc substrate take-out position A1 becomes empty, the disc substrate storage device ST1 is sequentially rotated by a predetermined angle. The disk substrate 1 can be supplied from the new disk holder 11 by rotating. The transfer device 2 includes three arms 2a, 2b and 2c for transferring the disk substrate 1 in synchronization with respective predetermined positions.

The disk substrate forming section R2 includes a temperature distribution forming / coating stage 3, a temperature distribution forming means 4 for forming a predetermined temperature distribution on the surface of the disk substrate 1, and an ultraviolet curable resin composition S as a disk. A coating device 5 for coating the inner peripheral portion of the substrate 1, a spin device 6 for uniformly spreading the ultraviolet curable resin composition S on the entire surface of the disk substrate 1, and an ultraviolet curable resin composition. And an ultraviolet irradiation stage 7 for curing S by ultraviolet irradiation. The temperature distribution forming / coating stage 3 is moved from the disc substrate take-out position A1 to the disc substrate 1 by the transfer device 2.
A disk loading position 3a, a temperature distribution forming position 3b where the surface of the disk substrate 1 is heated to form a predetermined temperature distribution, and the ultraviolet curable resin composition S is applied to the disk substrate 1 in an annular shape. Has a coating position 3c, a disk discharging position 3d for discharging the disk substrate 1 to the next step, and the like. In addition, the ultraviolet irradiation stage 7 includes the disk substrate 1
The ultraviolet-curing property that is spread on the surface of the disk substrate 1 by the ultraviolet-irradiating device 8 such as a flash irradiating device for the ultraviolet-curable resin composition S at the disk insertion position 7a where the temperature distribution formation / application stage 3 is introduced. The composition S has an ultraviolet irradiation position 7b for irradiating the composition S with ultraviolet rays, a disk discharging position 7c for discharging the disk substrate 1 to the next step, and the like.

The disc substrate inspection unit R3 takes out the disc inspection device 9 for judging the pass / fail of the disc substrate 1 and the disc substrate 1 at the disc ejection position 7c of the ultraviolet irradiation stage 7 and transfers it to the disc inspection device 9. And a transfer device 10 for performing the operation. The transfer device 10 is composed of two arms 10a and 10b for transferring the disk substrate 1 in synchronization with respective predetermined positions. The disk substrate storage unit R4 has a disk holder 11 on which a hardened film of the ultraviolet curable resin composition S is formed, and a disk substrate 1 which is a product is laminated, and the disk holder 1
Six of the product disk storage devices ST2 are arranged in an annular shape at predetermined intervals, and a defective disk storage portion A3 for storing the disk substrate 1 determined to be unacceptable by the disk inspection device 9. The disc substrates 1 judged to be acceptable by the disc substrate inspection device 9 are stored one by one on the uppermost layer of the disc holder 11 arranged at the product disc receiving position A2 in the product disc storage device ST2. The product disc storage device ST2 is configured to be rotatable in the direction of the arrow shown in the figure, and when the disc holder 11 arranged at the disc receiving position A2 is full, the product disc storage device ST2 is sequentially rotated to be a new (empty) disc. The disc substrates 1 are stacked and stored in the disc holder 11.

In the cured film forming apparatus 30 having the above-described structure, a temperature distribution is formed for forming a cured film of the ultraviolet curable resin composition S on the disc substrate 1 of the DV-R information recording disc. The means 4 will be described. In FIG. 3A, a holding table 32 that holds the disk substrate 1 and rotates integrally with the stage 3 is provided on the rotating temperature distribution forming / coating stage 3. With the holding table 32 reaching the temperature distribution forming position 3b and stopped, the temperature distribution forming means 4 is provided at a position facing the upper surface of the disk substrate 1. The temperature distribution forming means 4 is provided with a plurality of, for example, four light sources 34 in a lamp house 33, and a reflecting plate 35 is provided at the back of the light sources 34. As the light source 34, for example, SBC manufactured by USHIO INC.
The surface of the disk substrate 1 is heated by flash-irradiating a light beam containing infrared rays one or more times using a flash-irradiating device such as -13.

An opening 33a is formed on the lower surface of the lamp house 33.
Is perforated. A light amount adjusting member 36 (light amount adjusting member) made of, for example, a disk-shaped glass plate is fitted into the opening 33a. By appropriately selecting the length and the arrangement of the plurality of light sources 34, the distribution of the light intensity applied to the light amount adjusting member 36 becomes substantially uniform. Moreover, the light intensity reaching the disk substrate 1 by one flash and the flash interval are set so that the disk substrate 1 is not thermally deformed. The light amount adjusting member 36 is provided with a plurality of concentric light-shielding portions 38 on the surface thereof.
It is formed such that the amount of transmitted light in the central portion of the is reduced and the amount of transmitted light is gradually increased toward the outer peripheral side. When the amount of transmitted light is gradually increased outward in the radial direction by the light amount adjusting member 36, the intensity of light emitted to the surfaces of the disk substrates 1 that are arranged concentrically opposite to each other gradually increases from the central portion toward the outer peripheral side. Is distributed as As a result, the temperature distribution on the surface of the disk substrate 1 is also formed so as to gradually increase from the central portion of the surface of the disk substrate 1 toward the outer peripheral side. Moreover, it is preferable to control the concentric temperature on the surface of the disk substrate 1 to be uniform.

For example, the light quantity adjusting member 36 shown in FIG.
In the above, a circular first light-shielding portion 38a is formed in the center thereof, a ring-shaped second light-shielding portion 38b is formed outside thereof, and a ring-shaped third light-shielding portion 38c is formed outside thereof in order in concentric circles. The light shielding portion 38 is configured by
The radial widths of a, 38b, 38c, etc. gradually decrease toward the outer peripheral side, and each of the light shielding portions 38a, 38b, 38c.
And the like, as the transmitted light portions 39, a ring-shaped first transmitted light portion 39a, a second transmitted light portion 39b, and a third transmitted light portion 39c, respectively.
Etc. are formed, and the widths of the transmitted light portions 39a, 39b, 39c, etc. in the radial direction gradually increase toward the outer peripheral side. Further, another light amount adjusting member 3 shown in FIG.
In 6, while the surface is covered with the light shielding portion 38,
For example, the circular small transmitted light portions 30 are arranged in a concentric ring shape to form the first transmitted light portion 39a, the second transmitted light portion 39b, and the third transmitted light portion 39c as the transmitted light portion 39.
Then, for each of the ring-shaped transmitted light portions 39a, 39b, 39c, if the area of the inner diameter and the total sum of the small transmitted light portions 30 is set to be gradually increased toward the radially outer side, the transmitted light amount on the radially outer side with respect to the center side is set. Can be gradually increased. Alternatively, the intervals of the small transmitted light portions 30 of the transmitted light portions 39a, 39b, 39c may be gradually and densely arranged outward in the radial direction. In FIGS. 3B and 3C, the transmitted light portion 39 is
Although it is divided into two concentric rings, it is not limited to this and may be divided into four or more pieces, or may be formed into a non-ring shape and / or a non-concentric shape.

The cured film forming apparatus 30 according to the present embodiment has the above-mentioned structure. Next, the DV-using this apparatus is used.
A method of forming a cured film on the R disk substrate 1 will be described. First, in FIG. 1, a disc substrate 1 constituting a DV-R information recording disc is a surface 20 a of a substrate 20.
Visible light reflection layer 21, first dielectric layer 22A, phase change layer 2
Assuming that the third dielectric layer 22B and the second dielectric layer 22B are sequentially laminated in a ring shape and the transparent cured film 24 is not formed on the uppermost surface of the layer, this is supplied by the disk substrate supply unit R1. In the disk substrate supply unit R1 of the cured film forming apparatus 30 shown in FIG. 2, the disk substrate supply device ST1 is rotated to operate the disk holder 11 in which the disk substrates 1 are stacked.
Is moved to the disk substrate take-out position A1. Then, the transfer device 2 is operated and the disc holder 1 is moved by the arm 2a.
The disk substrate 1, which is the uppermost layer of No. 1, is conveyed to the disk loading position 3a of the temperature distribution forming / coating stage 3.

Subsequently, the temperature distribution forming / coating stage 3 is rotated one-quarter in the direction of the arrow in the drawing to move the disk substrate 1 to the temperature distribution forming position 3b. At the temperature distribution forming position 3b, as shown in FIG. 3A, a light source 34 (flash light irradiation device) irradiates the surface of the disk substrate 1 with a light beam including infrared rays at least once, so that the light amount adjusting member 36 is irradiated.
Is irradiated onto the surface of the disk substrate 1 to form a temperature distribution having a gradient in temperature rise according to the light intensity distribution. As a result, the disc substrate 1 has a small temperature rise range due to irradiation in the central portion where the ultraviolet curable composition S on the surface is hard to be deposited.
Are heated so that a temperature distribution is formed in which the width of the temperature increase gradually increases toward the outer peripheral side where the metal is easily deposited. The temperature distribution formed on the surface of the disk substrate 1 as described above is, for example, 25 ° C. and 10
30 ° C near 0 mm, 35 around the outermost 120 mm
℃. Subsequently, the temperature distribution forming / coating stage 3 is further rotated by a quarter turn in the direction of the arrow in the drawing to form the disk substrate 1 on which the above surface temperature distribution is formed.
To the coating position 3c for coating the ultraviolet curable resin composition S
To transport.

At the coating position 3c, as in the case shown in FIG. 4, the disk substrate 1 is rotated by a rotating means (not shown), and the ultraviolet curable resin composition S is discharged from the nozzle at the tip of the coating device 5. An annular ultraviolet curable resin composition S is formed on the inner surface of the second dielectric layer 22B, which is the outer surface of the disk substrate 1. At this time, it is preferable that a part of the annular ultraviolet curable resin composition S is applied on the surface 20a of the substrate 20 slightly inside the inner peripheral portion of the second dielectric layer 22B of the disk substrate 1. The viscosity of the UV curable resin composition S is 2000 mP at 25 ° C.
It is as, and the coating amount is set to about 2 to 3 times the required amount in consideration of the scattering of a part thereof to the outside. Disc substrate 1 on which the annular ultraviolet curable resin composition S is formed
Is transported from the coating position 3d to the spin device 6 by the arm 2b of the transfer device 2. Then, the disc substrate 1 is rotated by the spin device 6 at a rate of 1300 rpm, for example.
Spin for seconds. Thereby, the ultraviolet curable resin composition S
Are spread over the entire surface of the disk substrate 1. Here, in the case of normal spin spreading in which the temperature distribution is not formed on the surface of the disk substrate 1, the distribution of the formed film thickness gradually increases from the inner circumference to the outer circumference as described with reference to FIG. It tends to be deposited thicker on the outer peripheral side.

However, in this embodiment, as described above, the surface of the disk substrate 1 is provided with a temperature gradient such that the temperature gradually rises from the inner circumference to the outer circumference, and the liquid contacting the outer circumference having a high temperature is provided. The ultraviolet-curable resin composition S of No. 2 has a lower viscosity than the liquid ultraviolet-curable resin composition S in contact with the inner peripheral portion having a relatively low temperature, and is in a more easily spreadable (or slippery) state. . Therefore,
Since the ultraviolet curable resin composition S on the outer peripheral side is partly wrapped around the side surface or scattered to the outside, it is less likely to be deposited on the outer peripheral portion as in the conventional case, and the deposition amount is relatively reduced. Therefore, a liquid film made of the ultraviolet curable resin composition S having a uniform film thickness of, for example, about 0.1 m and excellent in flatness can be obtained from the inner surface to the outer surface. The disk substrate 1 on which the liquid film made of the ultraviolet curable resin composition S is formed in this manner is transported to the disk loading position 7a of the ultraviolet irradiation stage 7 by the arm 2c of the transfer device 2.

The disk substrate 1 conveyed to the disk loading position 7a is moved to the ultraviolet irradiation position 7 by rotating the ultraviolet irradiation stage 7 one third in the direction of the arrow shown.
b. The disk substrate 1 moved to the ultraviolet ray irradiation position 7b is irradiated with ultraviolet rays by the ultraviolet ray irradiation device 8, and the liquid film made of the ultraviolet curable resin composition S formed flat is cured to form the cured film 24. It becomes the disc substrate 1. Disk substrate 1 on which a cured film 24 is formed
Is rotated by the ultraviolet irradiation stage 7 in the direction of the arrow shown in FIG.
It is transported to c. The disc substrate 1 transported to the disc ejection position 7c is loaded into the disc inspection device 9 by the arm 10a of the transfer device 10. The disc substrate 1 that has been inspected by the disc inspection device 9 is the arm 1 of the transfer device 10.
By 0b, when the inspection is passed, the disc holder 1 is stacked on the disc holder 11 arranged at the product disc receiving position A2 of the product disc storage device ST2, and when the inspection is not passed, the disc holder 1 arranged in the defective disc storage unit A3.
1 are laminated respectively.

As described above, according to the present embodiment, the deposition of the outer peripheral portion due to the rotational spreading of the ultraviolet curable composition S is suppressed on the surface of the second dielectric layer 22B which is the outer surface of the disk substrate 1. The transparent cured film 24 can be formed with a uniform thickness, and the quality of the disk substrate 1 can be improved. In particular, even in the case of a DV-R information recording disc, which is regarded as a next-generation high recording density disc, the variation can be set within ± 3 μm with respect to the average thickness of 100 μm. Moreover, even if the conventional spin coating method is adopted, the cured film can be stably formed on the entire surface of the disk substrate.

In the above-mentioned embodiment, the temperature distribution is formed by heating the disk substrate 1 before applying the ultraviolet curable composition S to the surface of the disk substrate 1.
The present invention is not limited to such a configuration, and for example, the disk substrate 1 is heated before or during the step of spreading the ultraviolet curable composition S in an annular shape and then spreading the temperature distribution. May be formed. Alternatively, the temperature distribution may be formed by heating the ultraviolet curable composition S after spreading it over the entire surface of the disk substrate and before irradiating the ultraviolet light. In this case, since the thickness of the ultraviolet curable composition S is rearranged, it takes more time to adjust the thickness to be more uniform than the above case.

Although the light source 34 (flash light irradiation device) and the light quantity adjusting member 36 are used in the temperature distribution forming means 30 for the surface of the disk substrate 1, other means may be used.
For example, a high temperature object made of a metal such as aluminum or iron heated to a predetermined temperature may be brought into contact with or close to the surface of the disk substrate 1 and the degree of contact or proximity may be changed by heat conduction to form a temperature distribution. In this case, it is necessary to prevent the spreading of the liquid resin from being hindered by the contact with the high temperature object. Alternatively, the surface of the disk substrate 1 may be contacted through a heat-resistant thin cloth or an inclusion such as rubber or resin so as not to damage the surface. Particularly in the latter case, an appropriate temperature distribution can be formed by heating the high temperature object to the same temperature and adjusting the thickness of the inclusions according to the temperature distribution to be set. When the temperature distribution forming means is performed by light irradiation such as a flash light irradiation device or a continuous irradiation device, the temperature of the disk substrate may be controlled by irradiating the disk substrate 1 through an optical filter. Further, as the liquid resin, a resin composition other than the radical polymerization type ultraviolet curable resin composition such as the slow-acting cationic polymerization type ultraviolet curable resin composition may be used. Although the technique of forming the cured film 24 on the disk substrate 1 has been described in the above embodiment,
The present invention is not limited to this, and a cured film can be formed on various other base materials.

[0027]

As described above, according to the cured film forming body, the cured film forming method and the cured film forming apparatus of the present invention,
A cured film obtained by curing a liquid resin composition can be formed on the surface of a substrate with a uniform thickness.

If the temperature distribution is formed before the end of the coating process or at any timing during the spreading process, the efficiency of forming the cured film is high. When forming the temperature distribution, the temperature of the surface of the base material is uniform in the circumferential direction of the same radius, but a predetermined temperature gradient is provided in the radial direction. The thickness of the cured film is highly uniform.
Further, since the temperature distribution is formed by irradiation with light containing infrared rays, it is preferable in terms of irradiation efficiency to irradiate the base material with light rays containing a large amount of infrared rays (heat rays). Further, since the light irradiation is carried out by flashing once or twice or more, there is little damage or heat influence on the information recording layer of the base material even by light irradiation at a relatively high temperature,
Flash light irradiation can be repeated until a predetermined temperature distribution is formed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic structure of a DV-R disk substrate.

FIG. 2 is a diagram showing a schematic configuration of a cured film forming apparatus according to an embodiment of the present invention.

3A and 3B are diagrams showing a temperature distribution forming unit of the cured film forming apparatus shown in FIG. 2, wherein FIG. 3A is a configuration diagram of a main part of the temperature distribution forming unit, and FIG. 3B is a plan view showing an example of a light amount adjusting member. Figure,
FIG. 6C is a plan view showing another example of the light amount adjusting member.

4 (a), (b) and (c) are diagrams showing a coating and spreading process of a cured film using a conventional spin coating method.

[Explanation of symbols]

1 Disk substrate (base material) 4 Temperature distribution forming means 5 Coating device 8 UV irradiation device 24 cured film 30 Cured film forming device 34 Light source (flash irradiation device) 36 Light intensity adjustment member S UV curable resin composition

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/26 531 G11B 7/26 531 F term (reference) 4D075 AC64 AC92 AC96 BB25Y BB36Y BB37Y BB38Y BB42Z BB46Z BB93Y BB94Y CA02 CA48 CB06 DA08 DB48 DC27 EA21 4F042 AA02 AA08 DB19 DB21 DC01 EB29 EB30 5D121 AA04 EE22 EE24 EE28 EE30 GG02

Claims (11)

[Claims] 1. A surface of a substrate is formed in a predetermined temperature distribution state, and a liquid resin is uniformly applied to the surface of the substrate,
A cured film forming body, which is formed by curing this liquid resin to form a cured film. 2. A coating step of annularly applying a liquid resin onto at least the inner peripheral portion of the surface of the base material, and a spreading step of uniformly spreading the applied liquid resin by rotating the base material with the base material. And a method for forming a cured film by curing a liquid resin spread on the surface of the base material, the temperature for forming the surface of the base material in a predetermined temperature distribution state. A method for forming a cured film, characterized in that a distribution forming step is provided. 3. The method for forming a cured film according to claim 2, wherein the liquid resin is an ultraviolet curable resin composition. 4. The method for forming a cured film according to claim 2, wherein the temperature distribution is formed before the end of the coating step or at any timing during the spreading step. . 5. When forming the temperature distribution, the temperature of the surface of the base material is uniform in the circumferential direction of the same radius, but a predetermined temperature gradient is provided in the radial direction. The method for forming a cured film according to any one of 2 to 4. 6. The temperature distribution is formed by bringing a high-temperature object having a surface temperature of a predetermined temperature into contact with or close to a base material. The method for forming a cured film according to item 4. 7. The temperature distribution is formed by irradiation with light including infrared rays.
6. The method for forming a cured film according to any one of 5 to 5. 8. The method of forming a cured film according to claim 7, wherein the light irradiation is carried out by flashing once or twice or more. 9. A cured film forming apparatus configured to coat a liquid resin on a base material and cure the liquid resin, and a coating means for applying the liquid resin in an annular shape to at least an inner peripheral portion of the surface of the base material. A spreading means for uniformly spreading the applied liquid resin by rotating it with a base material, and a temperature distribution forming means for forming a surface of the base material in a predetermined temperature distribution state are provided. A cured film forming apparatus characterized by: 10. The cured film forming apparatus according to claim 9, wherein the temperature distribution forming means is provided with a light source and a light amount adjusting member for adjusting the amount of light emitted from the light source to the substrate. . 11. The cured film forming apparatus according to claim 10, wherein the light source is a flash light irradiation device that flashes light rays including infrared rays.