JP2002170284A - Optical information carrier and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information carrier provided with a photo setting sheet having an excellent characteristic in transferring information signals. SOLUTION: The optical information carrier is provided with the photo setting sheets 5 where the information signals 4a and 4b are transferred. The photo setting sheet with 20 mm width is adhered on a nickel board and irradiated with ultraviolet rays and, then, a 180 deg. peel test value under the condition of 300 mm/minute in drawing speed is made to be <=800 g. Thus the optical information carrier is provided, which has the photo setting sheet provided with the characteristic being excellent in transferring the information signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information carrier such as an optical disk or an optical card, and more particularly to an optical information carrier using a photocurable sheet for transferring an information signal for an optical disk and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art CD (Compact Disc) and DVD
Optical disks represented by (digital versatile disks) have permeated homes with remarkable momentum. Recently, a disc of the same size as a CD or DVD
The demand to have more than GB capacity is increasing,
Development is proceeding toward higher recording density. Increasing the recording density can be achieved by shortening the wavelength of the laser beam or increasing the numerical aperture (hereinafter, also referred to as NA) of the objective lens for irradiating the optical pickup with light for recording / reproducing.
This is possible by reducing the spot diameter of the reproduction light. When the NA of the objective lens is increased, it is necessary to reduce the thickness of the substrate on the incident surface side of the optical disk through which the reproduction light is irradiated and through which the reproduction light passes. This is the angle (tilt angle) at which the disk surface deviates from the perpendicular to the optical axis of the optical pickup.
This is because the tolerable amount becomes smaller, and the tilt angle causes optical aberrations, which leads to deterioration in reproduction signal quality. Therefore, the thickness of the substrate is reduced to minimize the amount of signal quality deterioration with respect to the tilt angle. Further, it is necessary to reduce the thickness unevenness of the incident surface layer of the disk for the same reason. For example, the laser wavelength is 780n
The thickness on the incident surface side of a CD having m and NA of 0.45 is about 1.2.
mmm, thickness unevenness is 200 μm or less,
Laser wavelength is 650nm, NA is 0.6 and recording capacity is C
DVD which is 6 to 8 times D has a thickness of about 0.6 mm and thickness unevenness of 60 μm or less. Also, as an example, 400n
at a wavelength near m and NA of 0.7 or more 2
In the case of a next-generation high-density optical disk of about 0 GB, the thickness on the incident surface side needs to be as small as about 0.1 mm and the thickness unevenness as small as 6 μm or less.

On the other hand, these optical disks are classified into a read-only type, a write-once type, and a rewritable type depending on the use. A conventional method of manufacturing an optical disk such as a CD or DVD is performed by a generally known injection molding method. With this injection molding method, a stamper, which is a master for pit or groove information signals, is attached to the mold of the injection molding machine, the molten resin is put into the cavity of this mold, and then cooled to cool the resin. This is a method of transferring an information signal by solidifying to obtain an optical disk substrate. Thereafter, a reflective film or a recording film is formed on the information signal surface of the substrate by sputtering or the like for the purpose, and a protective film or label printing is further performed thereon to obtain an optical disk.

In the case of a high-density optical disk having an incident surface layer having a thickness of about 0.1 mm, it is difficult to form an information signal of this substrate by an injection molding method because of its small thickness. Therefore,
Companies have come to adopt an information signal forming method using a 2P method or a photocurable sheet method, which has been used as a means of research and development, for normal production. The outline of this method is as follows. In the 2P method, a liquid photocurable resin is applied on a stamper, a light transmissive substrate is placed thereon, and the light curable resin is stretched. This is a method in which the photocurable resin is solidified by irradiating light from above, and an information signal is obtained on the light transmissive substrate by peeling off the space between the stamper and the photocurable resin. Further, the photocurable sheet method is a method of using a sheet which is in the form of a sheet at room temperature and which is completely cured by irradiating light, and the photocurable sheet is pasted on a stamper and further The information signal is transferred to the photocurable sheet by applying pressure while the light transmissive substrate is adhered to the substrate, and then the light curable sheet is completely solidified by irradiating light from the transparent substrate side, and the stamper and the photocurable This is a method of obtaining an information signal by peeling off between the conductive sheet and the conductive sheet.

[0005]

Among the information signal transfer methods described above, the method using a photocurable sheet, which will be described later, is suitable for mass production. Various methods for transferring information signals using the photocurable sheet have been disclosed. However, for example, see
According to the method disclosed in JP-A-334866, the properties such as uneven thickness and light transmittance are applied to the next-generation high-density optical disc, and the releasability from the stamper is adopted.
It was found that each of them, including the conventional products, was not sufficiently compatible. According to the technology disclosed in this publication, the viscosity of an uncured sheet is optimally 3500 to 400,000 poise. However, in the bonding operation using a photocurable sheet, since the sheet is used by being tilted, Is 3500
Poise had a drawback that the pressure-sensitive adhesive of the photocurable sheet moved in a short time, resulting in uneven thickness. On the other hand, when the viscosity is 4
In the case of 00000 poise, a large pressure is required to transfer a signal. Therefore, not only large-scale equipment is required, but also the unevenness of the information signal is reduced due to the high density, and good transfer is obtained with such a high viscosity. It has a drawback that it becomes difficult to perform. Furthermore, although the wavelength of the laser used for recording and reproduction of the next-generation high-density optical disk is around 400 nm, the light transmittance of the photocurable sheet also has a characteristic that it sharply decreases at around 400 nm. Degradation was also one of the drawbacks. Furthermore, a photocurable sheet is attached to a stamper on which an information signal is formed as a matrix, and a light-transmissive substrate is attached thereon. Then, the sheet is irradiated with light to solidify the sheet, and the stamper and the photocurable sheet are used. The information signal is transferred by peeling the gap, but depending on the type of this photocurable sheet, when it cannot be peeled or even if it peels, a crack occurs on the sheet surface, and the information signal also has a poor transfer such as destruction or deformation due to the crack. There is a drawback that there may be cases where

[0006] The present invention focuses on the above problems,
The present invention has been made to solve this problem effectively, and an object of the present invention is to provide an optical information carrier having a photocurable sheet having excellent characteristics for transferring information signals, and a method for manufacturing the same.

[0007]

The invention according to claim 1 is
In an optical information carrier having a photocurable sheet onto which an information signal has been transferred, the photocurable sheet is obtained by applying a 20-mm-wide light-curable sheet to a nickel plate and irradiating with ultraviolet light, and then applying a pulling speed of 300 mm / 180 ° in minutes
An optical information carrier characterized by being a photocurable sheet having a peel test value of 800 g or less. By using such a photocurable sheet, an information signal can be quickly and stably transferred from a stamper, and the mass productivity of an optical information carrier can be improved. An information signal is formed on a photocurable sheet surface of a sheet member in which a photocurable sheet and a light-transmitting substrate are integrated, and a reflective film is formed on the information signal surface. Is formed, and the reflective film and the optical information carrier substrate are bonded together with an adhesive, and the incident surface of the reproduction light when reproducing the information signal is performed from the light transmitting base material side. An optical information carrier characterized by the following.

According to a third aspect of the present invention, a first information signal is formed on a photocurable sheet surface of a sheet member in which a photocurable sheet and a light-transmitting substrate are integrated, and A semi-transparent film is formed on the information signal surface of the optical information carrier substrate on which the second information signal is formed, and a reflective film is formed on the second information signal surface of the optical information carrier substrate. The first and second information signal surfaces are bonded to each other with a light-transmitting adhesive facing each other, and the light-transmitting base material is used for reproducing the first and second information signals. An optical information carrier characterized by being performed from the side. According to a fourth aspect of the present invention, in the photocurable sheet on which the information signal is formed, a reflective film is formed on the information signal surface, and a light transmissive sheet is attached on the opposite surface. The sum of the thickness of the curable sheet and the thickness of the light transmitting sheet is smaller than that of the optical information carrier substrate, and the reflective film and the optical information carrier substrate are bonded to each other with an adhesive to reproduce the information signal. The optical information carrier is characterized in that the reproducing light is incident on the light transmissive sheet from the light transmitting sheet side.

According to a fifth aspect of the present invention, a translucent film is formed on the information signal surface of the photocurable sheet on which the first information signal is formed, and a light transmissive sheet is formed on the opposite surface. The sum of the thicknesses of the photocurable sheet and the light transmissive sheet is thinner than the optical information carrier substrate on which the second information signal is formed, and the second information signal surface has a reflective film. Is formed, and the first and second information signal surfaces are attached to each other with a light-transmitting adhesive facing each other, and the reproduction light when reproducing the first and second information signals is formed. The optical information carrier is characterized in that the light incident surface is formed from the light transmitting sheet side. The invention according to claim 6 is a method for manufacturing an optical information carrier having the above-described photocurable sheet, wherein the information signal is transferred by pressing the photocurable sheet onto a stamper on which an information signal is formed. Forming a photocurable sheet on which the information signal is formed by the method described above.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical information carrier according to the present invention and a method for producing the same will be described below in detail with reference to the accompanying drawings. In this embodiment, an optical disc will be described as an example of an optical information carrier. First, in the present invention, a photocurable sheet having the following characteristics is used as a photocurable sheet used for an optical information carrier in order to quickly and surely transfer an information signal from a stamper. That is, such a photocurable sheet has a 180 ° peel test value of 800 g or less under the condition of a pulling speed of 300 mm / min after applying a UV curable sheet having a 20 mm wide photocurable sheet to a nickel plate. It is a photocurable sheet as follows.

First, this kind of photocurable sheet is a sheet having a high viscosity and a semi-solid state at room temperature and looks like a solid at first glance, but it is deformed under low pressure and is exposed to ultraviolet light, electron beam or the like. It is completely cured by exposure to light. Because it is in the form of a sheet, it is easier to handle than a liquid photocurable resin. Also, the formation of information signals by the 2P method has advantages in the development stage of the disc, such as high transferability, etc., but an air layer is easily generated due to entrapment of bubbles and foreign substances, and the area around the air layer due to oxygen repellency is generated. The liquid photocurable resin tends to be in an uncured or semi-cured state, and it is difficult to obtain complete transfer over the entire surface. In contrast, as shown in FIG.
The curl of the photocurable sheet 5 to which the sheet 2 is joined is pressed gradually from the outer peripheral end of the stamper 3 toward the inner periphery by the rubber roller 11 or the like, so that air bubbles can be prevented from entering. Also, after pressing with the rubber roller 11,
By pressurizing the stamper 3 and the photocurable sheet 5 in a reduced-pressure atmosphere or a heated atmosphere, even if a small amount of air bubbles is mixed in, it is possible to completely deaerate the liquid, and use a liquid photocurable resin. It is more suitable for mass production than transfer.

As a method for bonding the stamper 3 and the photocurable sheet 5, there is another method shown in FIG. More specifically, a photocurable sheet 5 stretched with a constant tension is installed on the information signal surface of the stamper 3 on which the information signal 4 is formed (see FIG. 2A). The rubber roller 11 is joined while joining the photocurable sheet 5 from the end.
Press with. Photocurable sheet 5 on the pressed side
(A side) is equal to or lower than the level of the information signal surface of the stamper 3, and the photocurable sheet 5 (B side) on the side to be pressed is set higher than that level to prevent air bubbles from entering. This can be prevented (see FIG. 2B). Also, as shown in FIG. 3, a large rubber pad 18 partially having a spherical shape is used to gradually press outward from the center of the stamper 3 to prevent air bubbles from being mixed. Further, as shown in FIG. 4, the outer peripheral edge of the stamper 3 is pressed against the photocurable sheet 5 in a state where the stamper 3 is inclined, and the stamper 3 gradually becomes horizontal in the figure as the contact area between them increases. By joining in this manner, it is possible to prevent air bubbles from being mixed between the two. If the method shown in FIGS. 1 to 4 is performed while air or nitrogen is blown onto the surface of the stamper 3 or the surface of the photocurable sheet 5, foreign substances such as dust are less likely to be caught. Furthermore, if the static elimination of an ionizer or the like is also performed, the effect of preventing foreign matter from being caught can be further improved. At this time, the stamper 3 is held flat by a method using a magnet clamp or vacuum suction.

The form of the photocurable sheet 5 may be a single sheet or a type in which a protective sheet is integrally joined to one or both sides of a substrate. Usually, the protective sheet 12 made of polyethylene, polypropylene, etc. (thickness: 10 μm to 100 μm)
) Is formed, and this protective sheet 12 is used at the time of use.
Peel off and use. In addition, there are a type in which the adhesiveness and the adhesiveness are increased by irradiating light, and a type in which the adhesiveness and the adhesiveness are decreased. Applications are generally known, such as interlayer films for laminated glass, electronic material parts, sealing films for solar cells, and dicing tapes for wafers. Not all such photocurable sheets can be used for high density molding. The reason is that the photocurable sheet forms an information signal on one side or both sides, and mechanical characteristics and optical characteristics are required because recording / reproducing light passes through.

Specifically, one of them is viscosity. In the above-mentioned publication, the viscosity of the photocurable sheet is
The viscosity is 3500-400000 poise, but when the viscosity is 3500 poise, the thickness unevenness becomes large. In particular, a value required for a next-generation high-density optical disk, for example, 6 μm
It is difficult to get a good yield below. In the next-generation high-density optical disk (in one example, pit width 0.2 μm, depth 30 nm, pit length 0.2 μm, track pitch 0.4 μm), CD (pit width 0.8 μm, depth 1
20 nm, pit length 1 μm, track pitch 1.6 μ
m) and DVD (pit width 0.4 μm, depth 100 nm,
Pit length 0.4 μm, track pitch 0.74 μm)
Each specification is smaller than that of the information signal of (1). For example, when comparing the pressure required for transfer when the transfer time of a CD and that of a high-density optical disk are the same, the density is affected by the square of the viscous substance, and the density is 16 because the depth is proportional.
The pressure and the depth are reduced by a factor of three, and a pressure 13 times the pressure required for transferring the CD signal is required. Therefore, a large pressure is required to transfer a high-density information signal using a photocurable sheet having a viscosity of 400,000 poise, and large-scale equipment is required. Therefore, it is necessary to take measures to reduce the pressure at the time of transfer by lowering the viscosity coefficient by using a low-viscosity photo-curable sheet. The viscosity of the photocurable sheet in the case is preferably 5000 to 1
00000 poise, more preferably 8000 to 5
It turned out to be 0000 poise.

One of the characteristics is an increase in light transmittance. The optical disk is a system in which a laser beam is applied to an information signal surface and information of return light (reflected light) is read. Therefore,
If the return light is weak, recording and reproduction become unstable. In the case of a recordable optical disk such as an optical disk or a magneto-optical disk using an organic dye or a phase change medium, a large laser power is required at the time of recording, but an incident surface layer material that reduces the light transmittance is used. In some cases, recording cannot be performed due to a decrease in recording power. Generally, the light transmittance required for an optical disc is said to be 70% or more in one example, and preferably 80% or more. Also, C
The laser wavelength used for D and DVD is 600 nm or more, but the next generation high-density optical disk has a wavelength of 4 nm.
A laser near 00 nm is used. On the other hand, most of the photocurable sheets have a sharp decrease in light transmittance near a wavelength of 400 nm. For example, in the case of a next-generation high-density optical disk system having a wavelength of 400 nm, an NA of 0.7 or more, and a thickness of the incident surface layer of 0.1 mm, if the incident surface layer is constituted by a single photocurable sheet, the light transmittance of A decrease is considered. The light transmittance has a fixed relationship with the thickness. For example, a light-transmittance having a thickness of 100 μm and a light transmittance of 50% has a light transmittance of about 71% when the thickness becomes 50 μm and a light beam having a thickness of 30 μm. Since the transmittance is about 81%, and the light transmittance increases as the thickness decreases, the structure of the incident surface layer of the next-generation high-density optical disk is composed of a photo-curable sheet and a light-transmissive sheet. By combining them, an incident surface layer having a high light transmittance can be obtained. That is, an information signal is transferred to one side of the photocurable sheet, and a light transmissive sheet is bonded to the other side, and the incident surface layer is formed from the light transmissive sheet side. The bonding may be carried out using the tackiness or adhesiveness of the photocurable sheet. If the adhesive strength is weak, the sheet may be bonded using a transmissive adhesive such as a photocurable adhesive.

In the next-generation high-density optical disk, since the influence of aberration due to an increase in the NA of the lens increases, it is necessary to reduce the unevenness of the thickness of the incident surface layer. Have been done. This value can be obtained by the incident surface layer formed by laminating the light-transmitting sheet to the above-described light-curable sheet, but more preferably, the light-curing sheet integrated with the light-transmitting substrate is formed by the incident surface layer. The unevenness in thickness can be further reduced by using. This is because the light-curable sheet and the light-transmitting substrate are forcibly passed between parallel rolls together to create an integrated sheet member with less uneven thickness. It is. Suitable examples of the light-transmitting sheet and the light-transmitting substrate include a polycarbonate sheet, an acrylic sheet, a vinyl chloride sheet, and an amorphous polyolefin sheet.

Regardless of the combination of the light-curable sheet and the light-transmitting sheet, or the combination of the integrated light-curable sheet and the light-transmitting substrate, the thickness of the light-curable sheet is 400 times of the reproduction light.
Considering the light transmittance with respect to the wavelength of nm, it is preferably 50 μm or less, more preferably 30 μm or less. In addition, the lower limit value is about 10 μm, which is the minimum thickness at which the sheet can be formed in terms of strength if a photocurable sheet is used alone, and becomes the minimum thickness at which good transfer is possible when integrated with a light-transmitting substrate. For example, the depth of an information signal of a CD is 120
The thickness is about nm, but if the thickness is 5 to 10 times that, good transfer can be performed, so that the integral photocurable sheet only needs to be attached to the base material at least about 1 μm. FIG.
As shown in (1), the surface roughness of the surface of the light transmissive substrate 13 to which the photocurable sheet 5 is attached is, for example, the maximum surface roughness (Ra) is 1
Even in large cases such as μm, they pass together between the rolls, so that the photocurable sheet penetrates into the details of the roughness of the light-transmitting substrate, so that there is no generation of air bubbles and the like, and there is no transmission due to surface roughness. Light reduction can also be eliminated. Also in this case, good transfer can be performed if the thickness H of the photocurable sheet 5 in FIG. 5 is 5 to 10 times the depth of the information signal to be transferred. Further, as another requirement that must be taken into consideration, there is a refractive aberration of light at the reproduction wavelength of the light-curable sheet 5 and the light-transmitting substrate 13. If the difference in the refractive index between the light-transmitting substrate 13 and the photocurable sheet 5 is large, the amount of reflection at the boundary increases, causing adverse effects such as an increase in noise as well as a decrease in transmitted light. Therefore, the difference in refractive index between the light transmitting base material 13 and the photocurable sheet 5 is set to be 0.3 or less. According to this, it has been experimentally proved that even a high-density optical disk using a laser having a wavelength of 400 nm has no adverse effect on recording and reproduction.

Next, the adhesive strength and the adhesive strength will be described. For example, as shown in FIG.
After the photocurable sheet 5 having the protection sheet 12 on the information signal surface is pressed by the rubber roller 11 and bonded while transferring the information signal, the protection sheet 12 is removed, and instead a CD or DVD is manufactured. At times, put a light transmissive substrate,
When manufacturing a next-generation high-density optical disk, a light-transmitting sheet is placed, and after applying pressure, light is applied to completely solidify the light-curable sheet and solidify the information signal, and then light-curing The conductive sheet 5 is peeled off from the stamper 3. In addition, the method of peeling the sheet 5 is such that when the substrate is a light-transmitting substrate, the substrate 5 is peeled off from the outer peripheral portion of the substrate while being warped.
In the case of a next-generation high-density optical disk, the light-transmitting sheet is similarly peeled from the outer peripheral edge so as not to be creased. Further, a structure such that air or nitrogen gas for facilitating release is blown out to a table or the like to which the stamper 3 is fixed is blown to release the gas between the stamper and the photocurable sheet during peeling. You may do so.
At this time, if the adhesive strength or adhesive strength between the two is strong, the photocurable sheet 5 does not peel off from the stamper 3 when peeling off,
The surface of the photocurable sheet 5 may be cracked, and the information signal may be cracked, resulting in transfer failure such as destruction or deformation. As described above, in the case of a high-density optical disc, since the light-transmitting sheet is thin, it is stretched and the deviation of the signal train from a perfect circle becomes large, and the sheet itself may be cut. This is an important point when the curable sheet is used for transferring information signals.

As described above, the photocurable sheet may be of a type that increases the adhesiveness or adhesiveness by irradiating light such as an ultraviolet ray or an electron beam depending on the purpose, or a type that does not change. There are types that decrease.
In a test examining the relationship between the adhesive force (adhesive force) and transfer failure such as cracks in information signals, it was found that when the adhesive force was 800 g or less, good transfer could be performed without cracking. This measuring method was performed with reference to the 180 ° peel test method, which is a general adhesive test method used by each company among the adhesive test methods in JIS Z0237 which defines the adhesive tape / adhesive sheet test method. .

Specifically, the test method is described below. A 20-mm-wide photocurable sheet is adhered to a nickel plate made of the same material as the stamper, pressurized by a rubber roller, irradiated with ultraviolet rays, and The sheet was folded at 180 ° and the peeling force at a pulling speed of 300 mm / min was defined as the adhesive force (adhesive force). Regarding the control of adhesive strength,
For example, it is possible to reduce the adhesive strength or adhesive force between the stamper and the photocurable sheet by adding a release material during the production of the photocurable sheet or performing a release treatment on the information signal surface of the stamper. It is also possible to use a photocurable sheet having a structure such that the adhesive strength or the adhesive strength is reduced by irradiating light like a wafer dicing tape. As described above, the photocurable sheet whose adhesive strength is reduced by irradiating light is a low-curing sheet having at least two or more photopolymerizable carbon-carbon double bonds in a molecule which can be three-dimensionally reticulated by light irradiation. It is based on an adhesive consisting of a molecular weight compound. The condition of the peeling force test is an example. For example, there is a method of peeling off at right angles to an adherend (a stamper), and the pulling speed is only an example of the one performed at a speed specified in JIS. Yes, it is not limited to this, and after irradiating light to solidify the photocurable sheet, the presence or absence of information signal destruction or deformation due to cracks on the photocurable sheet surface peeled from the stamper and the photocurable sheet Is a method for expressing the relationship between the adhesive strength and the adhesive strength after irradiation.

Next, the form of a next-generation high-density optical disk will be described. As explained in the prior art,
The incident surface layer of the next-generation high-density optical disk is about 0.1 mm
Therefore, it is difficult to form this by a conventional injection molding method. On the other hand, in consideration of the total thickness of the high-density optical disk, it is preferable that the thickness is 1.2 mm, which is the same as that of a CD or DVD, in terms of handling.
Therefore, as one form of the next-generation high-density optical disk, for example, when the thickness of the incident surface layer is 0.1 mm, the substrate is 1.
1 mm. That is, the thickness of the incident surface layer is smaller than that of the substrate. In the embodiments described later, a read-only type (ROM type) optical disk is described. However, the present invention is not limited to this. For example, an organic dye is used as a recording layer on information signals such as guide grooves and address pits. A write-once optical disc on which an aluminum film or the like is provided as a cooling layer on which information can be recorded only once, a sublayer formed of a transparent material on a similar information signal, and recording using a phase change film as a medium. -Changeable optical disc that can be rewritten as many times as possible by providing an aluminum layer or the like as a layer, an overcoating layer made of a transparent material, or a cooling layer, or a phase-changeable disc that can be rewritten only once, and a similar optical signal on the information signal In addition to a single-layer structure having only one recording layer such as a magneto-optical disk that can be rewritten many times by providing a recording magnetic layer having an effect, an intermediate layer was obtained to make the film structure a target type. In the form of an optical disc having a two-layer structure having a recording layer of the layer can be applied. Furthermore, the present invention is not limited to an optical disk, but is also applicable to a card-shaped optical card, a card having a hole whose outer diameter is processed into a rectangular shape such as an optical disk, and the like.

<Embodiment 1> Hereinafter, a specific embodiment according to the present invention will be described in detail with reference to FIGS. 6, 7, 8 and Table 1. FIG. 6 is a schematic view for explaining a general 180 ° peel test method, and FIG. 7 is a method for transferring an information signal of a DVD using various photocurable sheets having different adhesive strengths (adhesive strengths). FIG. 8 is a schematic view for explaining, and FIG. 8 is a schematic view showing one embodiment of a DVD-type optical disk in which an information signal is formed by a photocurable sheet. Table 1 shows the adhesion of various photocurable sheets, observation results (cracked state and destruction or deformation of information signals) of the photocurable sheet surface when formed into an optical disc, and reproduction results. First, as a method for measuring the adhesive force (adhesive force or adhesive force is hereinafter referred to as adhesive force) of a photocurable sheet, as described above, the 180 ° peel test method used when measuring the adhesive force of an adhesive sheet or the like is used. went. This method will be described in detail with reference to FIG. A measuring sheet 2 having a constant width is adhered to the adherend 1 at a constant pressure, and the measuring sheet is folded back at 180 ° with respect to a laminating direction, and a peeling force when peeling the measuring sheet at a constant speed is defined as an adhesive force. How to This method is defined in JIS Z0237, and the adherend is S
Although US304 (stainless steel) is to be used, in this embodiment, a nickel plate made of the same material as the stamper is used in order to make the stamper more realistic. In addition, the transfer force differs depending on the viscosity of the photocurable sheet, etc.
Each was set to a pressure suitable for transfer. Specifically, a photo-curable sheet having a width of 20 mm was applied to a nickel plate having a thickness of 0.3 mm by applying pressure with a rubber roller, and was irradiated with ultraviolet light.
An 80 ° peel test was performed, and the peeling force at that time was measured as an adhesive force. In addition, since the irradiation conditions also differed depending on the photocurable sheet, the respective conditions were set to be suitable. The adhesion of the various photocurable sheets of Samples A to G was measured by the method described above, and the results are shown in Table 1.

Information signals were transferred from a stamper as a matrix using photocurable sheets having different adhesive strengths as shown in Table 1. The method will be described in detail with reference to FIG. Here, a DVD-ROM signal was used as the information signal. Stamper 3
A light-curable sheet 5 having a thickness of about 50 μm is placed on the information signal surface having the information signal 4 as shown in FIG.
Were bonded while pressing with a rubber roller 11 from the outer peripheral end of Further, the protective sheet 12 was removed, and the outer diameter was 120 mm, the inner diameter was 15 mm, and the thickness was 0.55 mm.
(Light information carrier substrate) 6 was bonded together.
Thereafter, pressure is applied in a reduced pressure atmosphere or a heating atmosphere, and the pressure is applied between the stamper 3 and the photocurable sheet 5 and between the stamper 3 and the photocurable sheet 5.
The deaeration between the substrate and the light-transmitting substrate 6 was completely performed. Then, after irradiating ultraviolet rays (not shown) from the light transmitting substrate 6 side, the stamper 3 and the photocurable sheet 5 were peeled off, and the information signal 4 was transferred to the sheet 5. In addition, the photocurable sheet 5 used was the same size as the substrate 6 with the inner and outer peripheries processed, but it may be cut after bonding.

An aluminum reflective film 7 is formed on the surface of the photocurable sheet 5 for the information signal 4 by sputtering, and the surface of the information signal 4 is placed on a dummy plate 8 having an outer diameter of 120 mm and a thickness of about 0.6 mm. The inside was bonded with an adhesive 9 to obtain a DVD-type optical disk 20 shown in FIG. Here, the information signal 4 before the above sputtering was observed with a microscope or the like, and the surface state such as destruction or deformation of the information signal due to cracks was examined. It is shown in Table 1.

[0025]

[Table 1]

As is clear from Table 1, the adhesive strength is 90.
In the case of 0 g or more, as shown in Samples E to G, cracks occurred, and destruction and deformation of the information signal were observed.
Also, when the reproduction result shows that the adhesive force is 900 g or more, deterioration such as generation of block noise starts to appear, and particularly, 1200
In the case of g or more, reproduction was not possible. On the contrary,
When the adhesive force was 800 g or less, as shown in Samples A to D, there was no crack and the reproduction result was good. Therefore, it was found that it is preferable to set the adhesive force to 800 g or less. The transfer of the information signal 4 may be performed by bonding the light-curable sheet 5 to the light-transmitting substrate 6 and then to the information signal 4 of the stamper 3. The dummy plate 8 was manufactured by injection molding using a polycarbonate resin. However, since it is not necessary to mold an information signal and it is not necessary to pass reproduction light, commercially available vinyl chloride resin and styrene resin Alternatively, a plastic plate such as an acrylic resin, a glass plate, a metal plate, or the like may be used.

<Embodiment 2> The form of a next-generation high-density optical disk using a photocurable sheet will be described below using Embodiments 2 to 5. First, a first embodiment of the present invention will be described in detail with reference to FIGS. FIG. 9 is a schematic diagram for explaining a method of transferring an information signal on a stamper as a matrix onto a photocurable sheet.
0 is a schematic diagram showing one embodiment of a two-layer structure of the high-density optical disk of the present invention. The basic configuration of the sheet shown in FIG. 9 is the same as that shown in FIG. First, a description will be given of the form of the optical disk. The optical disk 21 has a first information signal 4a on the surface of the light-curable sheet 5 of the sheet member in which the light-curable sheet 5 and the light-transmitting substrate 13 are integrated. Is formed on the upper surface (the lower surface in the figure) of the semi-transparent film 1.
The reflection film 7 is formed on the surface of the sheet member on which the film 4 is formed and the information signal 4b of the substrate 15 on which the second information signal 4b is formed, and the first and second information signal surfaces are formed. They are bonded to each other with a light transmitting adhesive 16 facing each other. When the first and second information signals are reproduced, the incident surface layer is formed from the light-transmitting substrate 13 side.

The method of manufacturing the optical disk 21 will be described in detail below. First, the first information signal 4 of the stamper 3
A sheet member in which the light-curable sheet 5 and the light-transmissive base material 13 are integrated on the surface of a, and the light-curable sheet 5 is placed downward from the outer peripheral end of the stamper 3 as shown in FIG. Lamination was performed while pressing with a rubber roller. In this case, a light-transmitting substrate 13 is used instead of the protective sheet 12 shown in FIG. 1, but the protective sheet 12 is placed on the light-transmitting substrate 13 for the purpose of protecting the light-transmitting substrate 13. In the case of a sheet having a three-layer structure (actually, a protective sheet is attached to both sides and thus has a four-layer structure) bonded with an adhesive or the like, the light transmitting base material 13 serving as the incident surface layer is not directly applied to the rubber roller. It is even better because it is a measure against dirt and scratches. Thereafter, pressure was applied in a reduced-pressure atmosphere or a heating atmosphere, and deaeration between the stamper 3 and the photocurable sheet 5 was completely performed. Then, after performing ultraviolet irradiation (not shown) from the light-transmitting substrate 13 side, the space between the stamper 3 and the photocurable sheet 5 was peeled off, and the first information signal 4a was transferred onto the photocurable sheet 5. The integrated light-curable sheet 5 and light-transmissive substrate 13 used in this example are for dicing tape (manufactured by Lintec Corporation), and the thickness of the light-curable sheet 5 is 20 μm. The thickness of the light transmitting substrate 13 is 80 μm, and the wavelength is 400 μm.
The sheet has a light transmittance of 86% at nm and an adhesive force of 20 g. Further, the sheet is cut into 15 mm in inner circumference and 120 mm in outer circumference having the same size as an injection molded substrate to be described later after signal transfer, but may be cut in advance. Further, the thickness unevenness was 3 μm. A silver translucent film 14 was formed on the surface of the first information signal 4a on the photocurable sheet 5 by sputtering.

In another step, the substrate 15 on which the second information signal 4b is formed by the injection molding method is manufactured. More specifically, the substrate 15 is made of an optical disk grade polycarbonate resin having a cylinder temperature of 380 ° C. melted in a mold (a mold set temperature of 115 ° C.) provided with a stamper which is a master of the second information signal 4b. And the polycarbonate resin is solidified by cooling, and the outer diameter is 120 mm and the inner diameter is 1
The substrate 15 containing the second information signal 4b having a thickness of 5 mm and a thickness of 1.1 mm was manufactured. Thereafter, the second information signal 4b
An aluminum reflective film 7 was formed on the surface by sputtering. The integrated body of the photocurable sheet 5 thus formed and the substrate 15 are separated from each other by the first information signal 4a and the second information signal 4a.
With the information signal 4b, and bonded by a spin bonding method with an ultraviolet-curable transparent adhesive 16 interposed therebetween to obtain a high-density two-layer optical disk 21. The intermediate layer (thickness of the adhesive) at this time was 30 μm. Further, a transparent adhesive sheet (manufactured by Nitto Denko Corporation) may be used instead of the transparent adhesive 16. This is made in advance so as to reduce the thickness unevenness, and thus has the effect of reducing the thickness unevenness of the intermediate layer. In addition, the inner diameter of the sheet member (integral body) in which the photocurable sheet 5 and the light-transmitting base material 13 are integrated is made larger than the inner diameter of the substrate 15, and the outer diameter is made smaller than that of the substrate 15, so that handling is possible. This has the effect of preventing peeling of the sheet. Further, although the substrate 15 is made of a polycarbonate resin, since the substrate 15 does not need to transmit light, another resin may be used as long as the transfer of the information signal 4b is good and the strength is the same or more.

<Embodiment 3> FIG. 11 is a schematic view showing one embodiment of a high-density optical disk of the present invention. This optical disk 2
In the optical disc 22, the information signal 4 is formed on the surface of the light-curable sheet 5 of the sheet member in which the light-curable sheet 5 and the light-transmitting substrate 13 are integrated. The reflective film 7 is formed thereon. The surface of the reflection film 7 of the sheet member and the substrate 8 (no information signal) are bonded with an adhesive 9.
In this optical disc 22, the incident surface layer when reproducing the information signal 4 is formed from the light transmitting base material 13 side. The manufacturing method of this disc will be described in detail below. The surface of the light-curable sheet 5 of the sheet member in which the light-curable sheet 5 and the light-transmitting substrate 13 are integrated by the same sheet and method as in Example 2 Was provided with an information signal 4 and cut to the same size as the substrate 8. An aluminum reflection film 7 is provided on the surface of the information signal 4.
Was formed by sputtering. Then, a polycarbonate substrate 8 (without an information signal) having an inner diameter of 15 mm, an outer diameter of 120 mm, and a thickness of 1.1 mm was produced by injection molding, and the substrate 8 was provided with the photocurable sheet 5 and the light-transmitting substrate. The surface of the information signal 4 of the sheet member integrated with the material 13 was bonded to the substrate 8 by a spin bonding method with an ultraviolet-curing adhesive 9 to obtain a high-density optical disk 22. The adhesive layer at this time was 5 μm. Further, the thickness unevenness of the sheet member forming the incident surface layer, in which the photocurable sheet 5 and the light transmissive substrate 13 were integrated, was 3 μm.

As in the second embodiment, the inner diameter of the substrate 8 is
By making the inner diameter of the sheet member in which the photocurable sheet 5 and the light transmitting base material 13 are integrated and making the outer diameter smaller than that of the substrate 8, there is an effect that the peeling of the sheet due to handling can be prevented. In this embodiment, the substrate 8 is made of a polycarbonate resin. However, since the substrate 8 does not need to input information signals and does not need to transmit light, if the strength is the same or more, the substrate 8 is made of another injection molding resin. Not limited thereto, a commercially available plastic plate may be used.

<Embodiment 4> FIG. 12 is a schematic view showing an embodiment of a two-layer structure of a high-density optical disk according to the present invention. The optical disc 23 will be described. In the optical disc 23, a semi-transparent film 14 is formed on the surface of the photocurable sheet 5 on which the first information signal 4a is formed, on the information signal 4a. The light transmissive sheet 17 is stuck on the opposite surface. The reflection film 7 is formed on the surface of the information signal 4b of the substrate 15 on which the second information signal 4b is formed. The first and second information signal surfaces are attached to each other with a light-transmitting adhesive 16 facing each other. In this optical disc 23, the first and second
When the two information signals are reproduced, the incident surface layer is formed from the light transmitting sheet 17 side. The method of manufacturing the optical disk 23 will be described in detail below.
A single photocurable sheet 5 having a protective sheet 12 formed thereon as shown in FIG. 1 was adhered to the surface of the first information signal 4 a while pressing the outer peripheral end of the stamper 3 with a rubber roller 11. Next, the protective sheet 12 was removed, and the light-transmitting sheet 17 was bonded on the photocurable sheet 5 in the same manner. Thereafter, pressure was applied in a reduced pressure atmosphere or a heating atmosphere to completely deaerate between the stamper 3 and the photocurable sheet 5 and between the photocurable sheet 5 and the light transmissive sheet 17. After that, ultraviolet irradiation (not shown) was performed from the light transmissive sheet 17 side, and then the stamper 3 and the photocurable sheet 5 were peeled off to transfer the first information signal 4a onto the photocurable sheet 5.

The light-curable sheet 5 (made by Hitachi Chemical Co., Ltd., 50 μm thick) and the light-transmitting sheet 17 (polycarbonate sheet, 50 μm thick) used in the present example were bonded together at a wavelength of 400 nm. Was 78%, and the adhesive force of this photocurable sheet 5 was 550 g. Alternatively, the light curable sheet 5 and the light transmissive sheet 17 may be bonded together first, and then the light curable sheet 5 may be placed on the stamper 3 to transfer the information signal 4a. Further, when the adhesive strength (adhesive strength) of the photocurable sheet 5 is weak, the photocurable sheet 5 may be bonded to the light transmissive sheet 17 with a light transmissive adhesive or the like. After the signal is transferred, the sheet has the same size as the injection molded substrate described later, the inner circumference is 15 mm, and the outer circumference is
Although cut to 20 mm, a pre-cut one may be used. The first information signal 4a on the photocurable sheet 5
Was formed on the surface by sputtering.

Further, the substrate 15 on which the second information signal 4b is formed is separately manufactured by the injection molding method as in the second embodiment.
An aluminum reflective film 7 was formed on the surface of the second information signal 4b by sputtering.

The photocurable sheet 5 thus formed
Of the first information signal 4
a and the second information signal 4b were opposed to each other, and bonded by a spin bonding method with an ultraviolet-curable transparent adhesive 16 interposed therebetween to obtain a high-density two-layer optical disk 23.
The thickness unevenness of the sheet member forming the incident surface layer of the disk 23 and integrating the photocurable sheet 5 and the light transmissive sheet 17 was 5 μm. Note that the use of a transparent pressure-sensitive adhesive sheet as in Example 2 has the effect of reducing the thickness unevenness of the intermediate layer. Further, by making the inner diameters of the photocurable sheet 5 and the light transmitting sheet 17 larger than the inner diameter of the substrate 15 and making the outer diameter smaller than that of the substrate 15, there is an effect that the peeling of the sheet due to handling can be prevented. Further, by making the inner diameter of the light-transmitting sheet 17 larger than the inner diameter of the light-curable sheet 5 and making the outer diameter smaller than that of the light-curable sheet 5, there is a further effect of preventing peeling. On the other hand, the substrate 15 is made of a polycarbonate resin, but since the substrate 5 does not need to transmit light, another resin may be used as long as the transferability is good and the strength is the same or more.

<Embodiment 5> FIG. 13 is a schematic view showing one embodiment of a high density optical disk of the present invention. This optical disk 2
According to the fourth embodiment, in the optical disc 24,
Information signal 4 of photocurable sheet 5 on which information signal 4 is formed
A reflective film 7 is formed on the surface, and a light transmitting sheet 17 is affixed on the opposite surface, and the surface of the reflective film 7 and the substrate 8 (no information signal) are adhered with an adhesive 9. They are made together. In this optical disc 24, an incident surface layer for reproducing an information signal is formed from the light transmitting sheet 17 side. The method of manufacturing the optical disc 24 will be described in detail below. First, the information signal 4 is provided on one surface of the photocurable sheet 5 by the same sheet and method as in Example 4, and the light transmissive sheet 17 is attached to the opposite surface. A combined sheet member was obtained. A reflective film 7 of aluminum was formed on the surface of the information signal 4 of the sheet member by sputtering. Then, similarly to Example 3, the inner diameter is 15 mm and the outer diameter is 120 m by injection molding.
m, polycarbonate substrate 8 having a thickness of 1.1 mm
(Without an information signal) is prepared, and a sheet member in which the photocurable sheet 5 and the light transmissive sheet 17 are integrated is formed on the substrate 8 with the information signal 4 surface facing the substrate 8 and ultraviolet rays. The high-density optical disk 24 was obtained by spin bonding with the curable adhesive 9 interposed therebetween. The thickness unevenness of the sheet member forming the incident surface layer of the optical disc 24 and integrating the photocurable sheet 5 and the light transmissive sheet 17 was 5 μm.

The sheet was cut to the same size as the injection-molded substrate, with the inner circumference being 15 mm and the outer circumference being 120 mm.
By increasing the inner diameter of the sheet member in which the sheet member is integrated and making the outer diameter smaller than that of the substrate 8, it is possible to prevent the sheet from peeling due to handling. Further, by making the inner diameter of the light-transmitting sheet 17 larger than the inner diameter of the light-curable sheet 5 and making the outer diameter smaller than that of the light-curable sheet 5, there is a further effect of preventing peeling. In this embodiment, the substrate 8 is made of a polycarbonate resin. However, since the substrate 8 does not need to input information signals and does not need to transmit light, if the strength is the same or more, the substrate 8 is made of another injection molding resin. Not limited thereto, a commercially available plastic plate may be used. In each of the above embodiments, a reflective film of aluminum or a translucent film of silver is formed on the signal forming surface and immediately bonded to each other, but the reflective film is formed on the reflective film for the purpose of protecting information signals from the convenience of the manufacturing process. Alternatively, a protective film such as an ultraviolet curable resin may be applied on the translucent film.
In addition, the incident surface layer of one form of the next-generation high-density optical disk shown in FIGS. 10 to 13, that is, the surface side of the light-transmitting substrate 13 in FIGS. 10 and 11, and the light-transmitting sheet in FIGS. An anti-scratch film or an anti-static film may be provided on the surface side of 17. Regarding the formation method, in the case of a scratch prevention film, an ultraviolet curable resin having a surface hardness after curing of 2H or more in pencil hardness by a spinner can be used to obtain an effect 1 to 4.
It may be provided with a thickness of 10 μm. Further, if an antistatic agent is added to the ultraviolet curable resin, an antistatic effect can be obtained. Further, the light-transmitting base material 13 and the light-transmitting sheet 17
An anti-scratch film or an anti-static film may be provided at the time of fabrication.

[0038]

As described above, according to the optical information carrier and the method for producing the same of the present invention, the following excellent functions and effects can be exhibited. By using a photocurable sheet as in the present invention, information signals can be quickly and stably transferred from a stamper, and mass productivity of optical information carriers can be improved. Therefore, a conventional optical disk and a next-generation high-density optical disk excellent in mass productivity can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view for explaining one method of attaching a transparent sheet to a stamper.

FIG. 2 is a schematic view for explaining one method of attaching a transparent sheet to a stamper.

FIG. 3 is a schematic view for explaining one method of attaching a transparent sheet to a stamper.

FIG. 4 is a schematic view for explaining one method of attaching a transparent sheet to a stamper.

FIG. 5 is a schematic diagram for explaining a method for alleviating surface roughness of a light-transmitting substrate when the surface roughness is large.

FIG. 6 is a schematic diagram for explaining a 180 ° peel test method.

FIG. 7 is a schematic diagram for explaining a method of transferring a DVD information signal using a photocurable sheet.

FIG. 8 shows a DV produced using the photocurable sheet of the present invention.
FIG. 2 is a schematic diagram of a D-type single-layer optical disc.

FIG. 9 is a schematic diagram for explaining a method of transferring an information signal of a next-generation high-density optical disk using a photocurable sheet.

FIG. 10 is a schematic view showing one embodiment of a next-generation high-density optical disk using the photocurable sheet of the present invention.

FIG. 11 is a schematic view showing an embodiment of a next-generation high-density optical disk using the photocurable sheet of the present invention.

FIG. 12 is a schematic view showing an embodiment of a next-generation high-density optical disk using the photocurable sheet of the present invention.

FIG. 13 is a schematic view showing an embodiment of a next-generation high-density optical disk using the photocurable sheet of the present invention.

[Explanation of symbols]

3 stamper, 4, 4a, 4b information signal, 5 photocurable sheet, 6 transmissive substrate (optical information carrier substrate),
7: Reflective film, 9: Adhesive, 12: Protective sheet, 13: Light transmissive substrate, 14: Translucent film, 15: Substrate with information signal, 16: Light transmissive adhesive, 17: Light transmissive sheet , 2
0, 21, 22, 23, 24 ... optical disc.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/26 531 G11B 7/26 531 F term (Reference) 5D029 HA06 JB02 JB06 JB13 JC04 KB06 MA17 MA33 MA42 RA02 RA04 RA12 5D121 AA01 AA05 AA06 AA07 DD06 DD13 DD18 EE26 EE28 FF03 FF11 GG02

Claims (6)

[Claims] 1. An optical information carrier having a photocurable sheet onto which an information signal has been transferred, wherein the photocurable sheet is obtained by attaching a 20 mm-wide photocurable sheet to a nickel plate and irradiating with ultraviolet light. An optical information carrier comprising a photocurable sheet having a 180 ° peel test value of 800 g or less at a pulling speed of 300 mm / min. 2. An information signal is formed on a light-curable sheet surface of a sheet member in which a light-curable sheet and a light-transmitting substrate are integrated, and a reflective film is formed on the information signal surface. The reflective film and the optical information carrier substrate are bonded together with an adhesive, and the reproducing light incident surface when reproducing the information signal is performed from the light transmitting base material side. Characteristic optical information carrier. 3. A first information signal is formed on a light-curable sheet surface of a sheet member in which a light-curable sheet and a light-transmitting substrate are integrated, and the first information signal is formed on the first information signal surface. A reflective film is formed on a second information signal surface of the optical information carrier substrate on which a second information signal is formed, wherein the first and second information The first and second signal surfaces are bonded to each other with a light-transmitting adhesive so as to face each other.
And an optical information carrier, wherein a reproduction light incident surface when reproducing the second information signal is formed from the side of the light transmitting base material. 4. A photo-curable sheet on which an information signal is formed, a reflective film is formed on an information signal surface of the photo-curable sheet, and a light transmissive sheet is affixed to the opposite surface thereof. And the thickness of the light-transmitting sheet is made thinner than the optical information carrier substrate, and the reflective film and the optical information carrier substrate are bonded together with an adhesive, so that the information signal is reproduced when reproduced. An optical information carrier, wherein light is incident on the light transmissive sheet side. 5. A semi-transparent film is formed on the information signal surface of the photocurable sheet on which the first information signal is formed, and a light transmissive sheet is attached on the opposite surface. The sum of the thickness of the light-curable sheet and the thickness of the light-transmitting sheet is smaller than that of the optical information carrier substrate on which the second information signal is formed, and a reflective film is formed on the second information signal surface. ,
The first and second information signal surfaces are bonded to each other with a light-transmitting adhesive so that the first and second information signal surfaces face each other.
An optical information carrier characterized in that an incident surface of a reproduction light when reproducing the information signal is formed from the light transmitting sheet side. 6. A method for producing an optical information carrier having a photocurable sheet on which an information signal is formed as defined in claim 1, wherein the photocurable sheet is formed on a stamper on which an information signal is formed. A method for manufacturing an optical information carrier, comprising: forming a photocurable sheet on which the information signal is formed by transferring the information signal by applying a roller pressure.