HK1173840A - Method for manufacturing optical storage media and apparatus for manufacturing same - Google Patents

Description

Method and apparatus for manufacturing optical recording medium

Technical Field

The present invention relates to a method and an apparatus for manufacturing an optical recording medium, and more particularly, to a method and an apparatus for manufacturing an optical recording medium having a plurality of recording layers.

Background

In recent years, in order to record/reproduce large-capacity data such as a moving image having a high image quality for a long time, it has been desired to develop an optical recording medium capable of further increasing the information density than in the past. Examples of such optical recording media capable of achieving high information density include blu-ray discs, and for example, BD-R having a laminated structure in which 1 medium is provided with 2 (two) recording layers. If such a multi-layering technique of providing 2 or more recording layers is adopted, the capacity can be increased without changing the recording density per 1 layer.

The intermediate layer of such a laminated multilayer optical recording medium is generally produced by a production method called PhotoPolymerization (hereinafter, sometimes referred to as "2P method"). According to the 2P method, for example, a 1 st reflective layer, a 1 st recording layer, an intermediate layer having irregularities for recording tracks, a 2 nd reflective layer, and a 2 nd recording layer are sequentially formed on a 1 st transparent substrate having irregularities for recording tracks formed thereon, and a protective layer is finally formed thereon, thereby producing an optical recording medium having a 2-layer structure.

In the 2P method, the intermediate layer is generally produced in the following manner. First, a radiation curable resin material or the like is applied on a substrate on which a recording layer or the like is formed, and then a radiation transmissive stamper having irregularities is placed thereon. Then, the stamper is peeled off after curing the radiation curable resin material and the like. The irregularities are thus transferred onto the surface of the radiation curable resin material, thereby forming the intermediate layer. Then, a recording layer and the like are formed on the intermediate layer, thereby producing an optical recording medium having a plurality of recording layers. The intermediate layer forms a part of the optical path of the recording/reproducing light to the at least one recording layer regardless of which side of the substrate or the protective layer the recording/reproducing light is incident on, and the optical uniformity of the intermediate layer has a large influence on the recording/reproducing characteristics.

Therefore, the intermediate layer formed by the 2P method is required to have a film thickness uniformity and optical property uniformity over the entire surface of the substrate to some extent or more. Generally, the following method is generally employed: a radiation-curable resin material is applied onto a substrate by a spin coating method, a radiation-transmissive stamper is placed thereon, and the resin material is cured by irradiation with radiation such as ultraviolet rays to form an intermediate layer (see patent document 1).

However, in the above-described conventional techniques, the occurrence frequency of defects such as uneven film thickness distribution of the intermediate layer over the entire surface of the substrate and the occurrence of bubbles in the intermediate layer is high, and it is difficult to stably and efficiently form the intermediate layer having excellent uniformity in optical characteristics.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-288259

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the technical problems occurring in the production of a laminated multilayer optical recording medium by the 2P method.

That is, an object of the present invention is to provide a method and an apparatus for manufacturing a laminated multilayer optical recording medium with improved manufacturing efficiency.

Means for solving the problems

In order to solve such problems, the gist of the present invention is as follows.

(1) A method for manufacturing an optical recording medium having a plurality of recording layers on a disk-shaped substrate having a center hole, and an intermediate layer having a concave-convex shape and made of a radiation-curable resin material between the plurality of recording layers, the method comprising the steps of: a first step of applying the radiation curable resin raw material between a radiation transmissive stamper and a substrate having the recording layer so that the radiation transmissive stamper and the substrate having the recording layer are overlapped; a second step of twisting the radiation transmissive stamper and the substrate having the recording layer in a state of being pressed in a direction of approaching each other, thereby extending the radiation curable resin material; a third step of irradiating the vicinity of the center hole of the substrate with radiation to cure the radiation-curable resin material; and a fourth step of curing the radiation curable resin material extending over the entire substrate having the recording layer while performing rotation of the substrate having the recording layer and the radiation transmissive stamper, in order to extend the radiation curable resin material over the entire substrate having the recording layer, the radiation transmissive stamper and the substrate having the recording layer being bonded.

(2) The method of manufacturing an optical recording medium according to (1), wherein the substrate and the radiation transmissive stamper are each formed with annular small protrusions at the following positions: the face side overlapped in the first step is positioned closer to the center hole side than the chucking region.

(3) The method for producing an optical recording medium according to (1) or (2), wherein the second step includes a twisting step of relatively rotating the radiation transmissive stamper and the substrate having the recording layer, and the rotation speed of the twist in the twisting step is set to 0.1rpm to 30rpm, the pressing width between twists is set to 10 μm to 100 μm, and the rotation angle of the twist is set to a range of 180 ° to 360 °.

(4) The method of manufacturing an optical recording medium according to any one of (1) to (3), wherein in the third step, a range to which the radiation is irradiated is within a radius of 15mm from a center of the substrate.

(5) The method for manufacturing an optical recording medium according to any one of (1) to (4), comprising, between the second step and the third step, the step of: the pressing is performed by applying a load of 50g to 100g between the radiation transmissive stamper and the substrate.

(6) The method for manufacturing an optical recording medium according to any one of (1) to (5), comprising, between the second step and the third step, the step of: the radiation curable resin material is subjected to reduced pressure suction from a central axis for fixing the radiation transmissive stamper and the central hole of the substrate.

(7) The method for producing an optical recording medium according to any one of (1) to (6), wherein the viscosity of the radiation curable resin material is between 50cP and 1000 cP.

(8) The method of manufacturing an optical recording medium according to any one of (2) to (7), wherein a total value of heights of the small projection of the radiation transmissive stamper and the small projection of the substrate is within ± 15 μm of a target film thickness of the intermediate layer, and a radial direction misalignment of the small projection of the radiation transmissive stamper and the small projection of the substrate is within 0.5 mm.

(9) The method for producing an optical recording medium according to any one of (6) to (8), wherein a suction pressure in the step of performing reduced-pressure suction of the radiation curable resin material from the central axis is in a range of-1 kPa to-20 kPa.

(10) An apparatus for manufacturing an optical recording medium having a plurality of recording layers on a disk-shaped substrate having a center hole, an intermediate layer formed of a radiation curable resin material and having a concave-convex shape between the plurality of recording layers, the apparatus comprising at least: a first unit that applies the radiation curable resin raw material between a radiation transmissive stamper and a substrate having the recording layer so that the radiation transmissive stamper and the substrate having the recording layer are overlapped; a second unit that twists the radiation transmissive stamper and the substrate having the recording layer in a state of being pressed in a direction of approaching each other, thereby extending the radiation curable resin material; a third unit that cures the radiation-curable resin material by irradiating radiation only in the vicinity of the center hole of the substrate; and a fourth unit that cures the radiation curable resin material extending over the entire substrate having the recording layer while performing rotation of the substrate having the recording layer and the radiation transmissive stamper, and bonds the radiation transmissive stamper and the substrate having the recording layer.

Effects of the invention

According to the present invention, an optical recording medium including an intermediate layer having optically uniform characteristics over the entire surface can be manufactured. In addition, the manufacturing efficiency of the laminated multilayer optical recording medium by the 2P method can be improved.

Drawings

Fig. 1 is a diagram for explaining a method of manufacturing an optical recording medium of the present invention.

Fig. 2 is a diagram for explaining a gap distribution method (gap distribution).

Fig. 3 is a diagram for explaining the positions of the hammers and the light-shielding masks used in the method for manufacturing an optical recording medium of the present invention.

Fig. 4 is a sectional view of a small projection of a substrate for use in explaining the present invention.

Fig. 5 is a diagram for explaining a manufacturing apparatus of an optical recording medium of the present invention.

Detailed Description

Hereinafter, a mode for carrying out the present invention (hereinafter, also referred to as an embodiment of the invention) will be described in detail. However, the present invention is not limited to the embodiments of the invention described below, and it is needless to say that various modifications can be made without departing from the scope of the invention.

A. Preferred embodiment of the method for producing an optical recording medium of the present invention

Fig. 1 is a diagram for explaining a preferred example of a method for manufacturing an optical recording medium of the present invention. Fig. 1 shows a method for manufacturing a dual-layer single-sided incident type optical recording medium (single-sided 2-layer DVD-R or single-sided 2-layer DVD recordable optical disc) having two recording layers containing an organic dye, as an example of a method for manufacturing a stacked multilayer optical recording medium. For convenience, fig. 1 is an enlarged cross-sectional view of only a part of the recording area of the optical recording medium.

The single-sided 2-layer optical recording medium 100 represented by the single-sided 2-layer DVD-R shown in fig. 1 (f) has a structure in which the following parts are sequentially stacked: a disk-shaped (disk-shaped) translucent first substrate 101 having a center hole; a 1 st recording layer 102 containing a dye; a translucent 1 st reflective layer 103; a light-transmitting intermediate layer 104 made of a radiation-curable resin material; a 2 nd recording layer 105 containing a coloring matter; the 2 nd reflective layer 106; an adhesive layer 107; and a 2 nd substrate 108 forming an outermost layer. The 1 st substrate 101 and the intermediate layer 104 have irregularities formed thereon, respectively, and form recording tracks, respectively. Optical information is recorded/reproduced on/from the optical recording medium 100, which is a single-sided 2-layer DVD-R, by a laser beam 109 irradiated from the 1 st substrate 101 side to the 1 st recording layer 102 and the 2 nd recording layer 105.

In the embodiment of the present invention, the term "light-transmitting property (or transparency)" refers to a light-transmitting property with respect to the wavelength of light (laser light 109) irradiated for recording/reproducing optical information on/from the 1 st recording layer 102 and the 2 nd recording layer 105 including a dye. Specifically, the optical film has a transmittance of usually 30% or more, preferably 50% or more, and more preferably 60% or more, with respect to the wavelength of light for recording/reproduction. On the other hand, the transmittance for the wavelength of light for recording/reproduction is preferably 100%, but is usually 99.9% or less.

The present invention relates to a method for manufacturing an optical recording medium having a plurality of recording layers on a disk-shaped substrate having a center hole, and an intermediate layer having a concavo-convex shape made of a radiation-curable resin material between the recording layers, wherein the step of forming the intermediate layer includes first to fourth steps described later. In the embodiment of the present invention, the material and the production method of each layer other than the intermediate layer are not particularly limited, and can be appropriately formed by a known conventional technique.

For example, the 1 st substrate 101 shown in fig. 1 (a) having grooves, lands (ランド), and prepits formed on the surface thereof in an uneven manner can be produced by injection molding or the like of a polycarbonate resin using a nickel stamper or the like. Then, the 1 st recording layer 102 can be formed by applying a coating liquid containing an organic pigment to the surface of the 1 st substrate 101 having the irregularities by spin coating or the like, and then removing a solvent or the like used in the coating liquid by heating or the like. After the 1 st recording layer 102 is formed, for example, an Ag alloy or the like is sputtered or vapor-deposited, whereby the 1 st reflective layer 103 can be formed on the 1 st recording layer 102.

After the step of forming the intermediate layer 104 described later, as shown in fig. 1 (d), a coating liquid containing an organic dye is applied to the surface of the intermediate layer 104 by spin coating or the like, and a solvent or the like used in the coating liquid is removed by heating or the like, whereby the 2 nd recording layer 105 can be formed. In this case, the heating temperature is preferably a temperature equal to or higher than the glass transition temperature of the resin constituting the intermediate layer 104. By heating at the above temperature, it is possible to suppress a phenomenon that warpage is generated in the 1 st substrate 101, which is considered to be caused by shrinkage of the intermediate layer 104. In the embodiment of the present invention, the 2 nd recording layer 105 is formed directly on the intermediate layer 104, but the 2 nd recording layer 105 may be formed with another layer (for example, a protective layer or a buffer layer) interposed therebetween.

As shown in fig. 1 (e), the 2 nd reflective layer 106 can be formed on the 2 nd recording layer 105 by performing sputtering deposition or the like on an Ag alloy or the like. Then, as shown in fig. 1 (f), the 2 nd substrate 108, which is a mirror substrate obtained by injection molding of polycarbonate, is attached to the 2 nd reflective layer 106 via the adhesive layer 107, and the optical recording medium 100 is completed.

The adhesive layer 107 may be opaque, the surface may be slightly rough, and a delayed curing type adhesive or the like may be used. For example, an adhesive is applied to the 2 nd reflective layer 106 by a method such as screen printing, and ultraviolet rays are irradiated, and then the 2 nd substrate 108 is placed and pressed, thereby forming the adhesive layer 107. Alternatively, the adhesive layer 107 may be formed by sandwiching and pressing a pressure-sensitive double-sided tape between the 2 nd reflective layer 106 and the 2 nd substrate 108.

As described above, the layer structure of the optical recording medium of fig. 1 (f) is an example of an optical recording medium having two recording layers. Therefore, it is needless to say that other layers (for example, a base layer formed between the 1 st substrate 101 and the 1 st recording layer 102) not shown in fig. 1 (f) may be used.

Next, the formation steps (first to fourth steps) of the intermediate layer 104 will be described by taking as an example a case where the intermediate layer 104 is formed on the data substrate 111 in which the 1 st recording layer 102 and the 1 st reflective layer 103 are sequentially laminated on the 1 st substrate 101 shown in fig. 1 a, as the data substrate 111. In addition, in the embodiment of the present invention, the data substrate 111 is generally transparent.

(1) First step of

In this step, a radiation curable resin material is applied between the radiation transmissive stamper and the substrate having a recording layer (here, a data substrate), and the radiation transmissive stamper and the substrate having a recording layer are superposed.

Specifically, as shown in fig. 2, an ultraviolet-curable resin material 104a (hereinafter, when the radiation-curable resin material is an ultraviolet-curable resin material, referred to as the ultraviolet-curable resin material 104a, and when the radiation-curable resin material is broadly referred to as the radiation-curable resin material, referred to as the radiation-curable resin material 104 a) which is one kind of radiation-curable resin material is continuously or intermittently applied to the surface of the data substrate 111 on the 1 st reflective layer side by a nozzle or the like in a substantially annular shape concentric with the data substrate 111, and as shown in fig. 1 (c), a radiation-transmissive stamper 110 having an uneven shape is stacked. The ultraviolet curable resin material 104a may be applied to the surface of the radiation transmissive stamper 110, or may be applied to a gap between the data substrate 111 and the radiation transmissive stamper 110 (hereinafter, referred to as two substrates) while being superposed (that is, disposed to face each other).

In the above-described steps, the ultraviolet-curable resin material 104a is preferably applied by a method in which the data substrate 111 and the radiation-transmissive stamper 110 are stacked (i.e., arranged to face each other), and then the nozzle is inserted into the gap. This method is called a gap allocation method, and will be described below with reference to fig. 2.

For example, the radiation transmissive stamper 110 is disposed on the upper side, the data substrate 111 is disposed on the lower side, and the center holes of both are substantially aligned and disposed in a balanced manner, and the gap between both substrates is fixed to about 2 to 4 mm. One or more nozzles having a diameter of about 1.5mm are inserted into the gap laterally from the outer peripheral side of the substrate, and are arranged so that their ejection ports are located in the vicinity of the center of the intermediate layer formation region. The tips of the plurality of nozzles are preferably arranged on a concentric circle at equal intervals. In this state, when the ultraviolet curable resin material 104a is discharged from the nozzle tip, the distance between the two substrates is close to each other, and therefore the discharged ultraviolet curable resin material 104a immediately contacts the two substrates 110 and 111, and extends in the gap between the two substrates by capillary action. At this time, the ultraviolet curable resin material 104a can be applied in a substantially annular shape by rotating the nozzle or data substrate 111 and the radiation transmissive stamper 110 in the circumferential direction of the data substrate 111. After the ejection of a predetermined amount of the ultraviolet-curable resin material 104a is completed, the nozzle is retracted, and the ultraviolet-curable resin material 104a is further extended by lowering the radiation-transmissive stamper 110 disposed on the upper side or raising the data substrate 111 disposed on the lower side. This makes it possible to realize coating with less generation of bubbles in the external curable resin material 104 a.

When the data substrate 111 and the radiation transmissive stamper 110 are stacked, it is preferable that the center holes of the two substrates 110 and 111 penetrate the same center axis of the apparatus for manufacturing an optical recording medium, and that the eccentricity of the two substrates be adjusted to be within 30 μm.

It is preferable that annular small projections as shown in fig. 4 be formed in advance on the side of the data substrate on which the 1 st substrate 101 and the radiation transmissive stamper 110 are superimposed. Fig. 4 (a) is a view schematically showing the 1 st substrate 101, and fig. 4 (b) is a cross-sectional view of a-a line portion of fig. 4 (a). For example, the small projections may be formed at desired positions by a known method such as designing the position and shape of the mold pressing at the time of molding the 1 st substrate 101 or the radiation transmissive stamper 110.

The annular small projection is preferably formed at a position closer to the center hole side than a chucking region of the optical recording medium (the chucking region refers to a region chucked by a recording/reproducing apparatus of the optical recording medium, and is generally a region having a radius of about 11.5mm to 16.5mm from the center of the optical recording medium). Therefore, it is preferable that the 1 st substrate 101 among the data substrates is formed with a small annular projection in a region having a radius of 8.5 to 11.5mm from the center of the 1 st substrate 101, and the radiation transmissive stamper 110 is formed with a small annular projection in a position corresponding to the region.

Further, as for the height of the small projections, the total value of the heights of the small projections of the two substrates is preferably within a range of ± 15 μm, more preferably within a range of ± 5 μm of a desired intermediate layer film thickness. Here, the height of the small projection is a height based on the data recording area where the recording track is formed. By setting the height of the small projections to such a range, the distance between the two substrates can be set to an ideal range when the two substrates are stacked and pressed, and a desired thickness of the intermediate layer can be easily obtained. The cross-sectional shape of the small projection is not particularly limited, and may be any of a rectangular shape, a triangular shape, and a semicircular shape.

Further, the positional relationship in the radial direction of the two small projections when the two substrates are opposed to each other is preferably 0.5mm or less, more preferably 0mm, in the radial direction of the apexes of the two small projections. The two small projections have close radial positions, so that the extension of the ultraviolet curable resin material in the direction of the center hole can be prevented by the annular small projections, and the intermediate layer can be formed at a desired position.

(2) Second step of

In the second step, the two substrates stacked in the first step are pressed in a direction to approach each other, and the two substrates are twisted while the interval between the two substrates is further reduced.

The pressing width at this time depends on the amount of the ultraviolet curable resin material and the interval between the materials when the ultraviolet curable resin material is superimposed, but is preferably 10 μm or more, and more preferably 30 μm or more. Further, it is preferably 100 μm or less, more preferably 60 μm or less. The pressing width in the present invention is a relative movement distance of the two substrates when the interval between the two substrates is further reduced in the second step.

In this step, for example, one of the two substrates to be stacked is fixed and the other substrate is rotated in the circumferential direction by relatively rotating the two substrates to be stacked simultaneously with the above-described pressurization, whereby the applied ultraviolet-curable resin material 104a is extended on the surfaces of the two substrates. In this specification, the relative rotation of the two substrates in this step is referred to as "twisting", and this step is referred to as a twisting step. In addition, the two substrates may be twisted by rotating in opposite directions. The pressing of the two substrates may be performed before the twisting of the two substrates, or the twisting may be performed while the pressing is performed with the interval between the two substrates reduced. By performing the twisting step, the ultraviolet curable resin material 104a applied can be further extended on both substrate surfaces. The relative rotation speed when twisting the two substrates is preferably 0.1rpm or more, more preferably 10rpm or more. Further, it is preferably 30rpm or less, more preferably 20rpm or less. The ultraviolet curable resin material tends to be more uniformly spread as the rotation speed is lower, but is preferably higher from the viewpoint of production efficiency. The relative rotation angle when twisting the two substrates also depends on the mechanical accuracy of the parallelism of the turntable of the apparatus for producing optical recording media and the rotation speed, and is preferably 180 ° to 360 °. If the amount is within this range, the influence on the production efficiency is reduced, and the ultraviolet-curable resin material 104a tends to spread uniformly over both substrates.

(3) Step of pressurizing

In the embodiment of the present invention, it is preferable to have a step of applying a predetermined load between the radiation transmissive stamper 110 and the data substrate 111 after the second step and before a third step described later.

Specifically, as shown in fig. 3 (a), it is preferable that the radiation transmissive stamper 110 is disposed on the upper side, and a weight 120 is placed on the radiation transmissive stamper 110, thereby pressing the space between the two substrates 110 and 111. In fig. 3 (a), the hammers are arranged in a region of a radius of 7.5mm to 28mm from the center of the data substrate 111 in order to extend the ultraviolet-curable resin material 104a further toward the center hole of the data substrate 111, but the positions where the hammers are arranged can be appropriately adjusted according to the viscosity of the ultraviolet-curable resin material 104a and the like.

The weight load of the hammer at this time is preferably 50g or more, more preferably 70g or more. Further, it is preferably 100g or less, more preferably 90g or less. If the content is within this range, the ultraviolet-curable resin material 104a can be extended to a desired range. As shown in fig. 3 (a), the pressurization may be performed by a plurality of hammers, or may be performed by one hammer. The example shown in fig. 3 (a) is an example in which a hammer 120 of a quartz ring for pressurizing the vicinity of the center hole and a 1 st light-shielding hammer 121 outside thereof and a 2 nd light-shielding hammer 122 further outside thereof are arranged to perform predetermined pressurization. Here, the pressurization is performed by placing a hammer, but the pressurization may be performed by a known mechanical pressurization method.

Further, it is preferable that the hammers disposed near the center hole are made of a material that sufficiently transmits radiation so as to perform radiation irradiation in the third step described later. When the radiation as the third step is irradiated with ultraviolet rays, it is preferable that the hammer disposed near the center hole is made of a material that sufficiently transmits ultraviolet rays. In the embodiment of the present invention (ultraviolet irradiation method), in order to achieve both ultraviolet light transmittance and a certain load, it is preferable that the hammer disposed in the vicinity of the center hole is a ring of synthetic quartz that transmits ultraviolet light. In the case where a hammer made of a material through which ultraviolet rays do not sufficiently transmit is used as the hammer, it is preferable that the hammer made of a material through which ultraviolet rays do not sufficiently transmit be placed in a region having a diameter of 20mm or more so as not to be a shadow of the hammer in a region having a diameter of 20mm or more from the center of the disk when ultraviolet rays are irradiated in the third step described later.

Before the ultraviolet irradiation according to one embodiment of the third step, as shown in fig. 3 (a), it is preferable that a fine hole 124 for suction is opened in a side surface of a center shaft 123 for fixing center holes of the two substrates 110 and 111, and the ultraviolet-curable resin material 104a is sucked under reduced pressure from the fine hole, thereby increasing the speed of stretching the ultraviolet-curable resin material to the center hole side. Thus, the time taken for the ultraviolet curable resin material 104a to reach the annular small projection formed on the data substrate 111 side and the radiation transmissive stamper 110 is shortened as compared with the case where the reduced pressure suction is not performed, and the tact time can be shortened. The optimum suction pressure at this time depends on the viscosity of the ultraviolet curable resin material 104a, the surface shape of the data substrate 111, and the like, but is preferably in the range of-1 kPa to-20 kPa.

(4) The third step

Then, a third step of irradiating radiation only to the vicinity of the center hole of the substrate and curing the radiation curable resin material is performed.

Specifically, immediately after the ultraviolet-curable resin material 104a reaches the annular small protrusions of the two substrates 110 and 111, ultraviolet rays are irradiated only near the center hole of the substrates, and the ultraviolet-curable resin material 104a in the region is cured, as shown in fig. 3 (b). If the irradiation range is too large at this time, the ultraviolet-curable resin material 104a, which causes the naturally extending unevenness of the film thickness, is directly cured in a wide range, and even if the film thickness is made uniform by rotating the two substrates 110 and 111 at a high speed in the fourth step, the film thickness distribution near the irradiation range may be disturbed. Therefore, the irradiation range at this time is preferably limited to a range as far as possible from the information recording area of the optical recording medium for which high film thickness accuracy is required. In addition, if the irradiation range is too small, curing at the inner peripheral end is insufficient, and there is a possibility that air enters the ultraviolet-curable resin material 104a from the inner peripheral ends of the two substrates during the rotational stretching in the fourth step.

The most preferable irradiation range is a region having a radius of 8mm or more, more preferably a region having a radius of 10mm or more, and particularly preferably a region having a radius of 11mm or more from the center of the data substrate 111 (particularly the first substrate) and the radiation transmissive stamper 110. Further, a region having a radius of 15mm or less from the center of the data substrate 111 (particularly the first substrate) and the radiation transmissive stamper 110 is preferable, a region having a radius of 14mm or less is more preferable, and a region having a radius of 13mm or less is particularly preferable. If the thickness falls within this range, air does not enter the ultraviolet-curable resin material 104a when the ultraviolet-curable resin material is stretched in the fourth step described later, and a uniform film thickness distribution can be obtained. The amount of ultraviolet light and the irradiation time may be appropriately optimized depending on the material of the ultraviolet curable resin material and the production environment, and is usually about 20mW/cm²～200mW/cm²0-5 seconds.

Further, in order to irradiate only the above-described limited region with ultraviolet rays, a light shielding mask having a circular opening with a desired radius may be provided on the center hole, but in order to prevent blurring of the boundary of the irradiation region due to diffraction of ultraviolet rays, it is preferable to provide the light shielding mask in parallel at a position within 1mm from the upper surface of the radiation transmissive stamper 110. Further, as shown in fig. 3 b, for example, the above-described pressing hammer can also be made to function as a light shielding mask by using an ultraviolet-transmitting synthetic quartz ring in a region irradiated with ultraviolet rays (a region on the center hole side) and using light-shielding hammers 121 and 122 in regions not irradiated with ultraviolet rays.

(5) The fourth step

Then, such a fourth step is performed: in order to extend the radiation curable resin raw material over the entire substrate having the recording layer, the radiation curable resin raw material extending over the entire substrate is cured while performing rotation of the substrate having the recording layer and the radiation transmissive stamper, and the radiation transmissive stamper and the substrate having the recording layer are bonded.

Specifically, the light-shielding mask, the hammer, or the like used in the third step is removed, the two substrates 110 and 111 are fixed on a rotary table capable of rotating at a high speed, and the substrate is rotated at a high speed (spin-coated), whereby the ultraviolet-curable resin material 104a is further extended to the outer peripheral portions of the two substrates, and the ultraviolet-curable resin material 104a is cured, whereby a layer 104a made of an ultraviolet-curable resin material (hereinafter, a layer made of a radiation-curable resin material including an ultraviolet-curable resin material is also referred to as a resin material layer 104 a) is formed, and the radiation-transmissive stamper 110 and the data substrate 111 are bonded.

The rotation speed in spin coating is usually about 500 to 15000 rpm.

While the two substrates are being rotated, ultraviolet rays are irradiated from the radiation transmissive stamper 110 side to the entire surfaces of the two substrates 110 and 111 through the radiation transmissive stamper 110, the ultraviolet curable resin material 104a is cured, and when the curing is sufficiently performed, the radiation transmissive stamper 110 is peeled off, thereby forming the intermediate layer 104.

The thickness of the intermediate layer can be set appropriately according to the type of optical recording medium, and the thickness of the intermediate layer of the single-sided 2-layer DVD-R is about 55 μm.

In the embodiment of the present invention, in order to improve the uniformity of the thickness of the intermediate layer, the ultraviolet-curable resin material is stretched by the rotation of the two substrates, and the curing step of the ultraviolet-curable resin material is performed. Here, in a general spin coating method, since the film thickness of the resin material layer tends to be thin at the inner peripheral portion and thick at the outer peripheral portion due to centrifugal force, the uniformity of the film thickness of the intermediate layer at the inner and outer peripheries can be further improved by performing spin stretching and ultraviolet curing while performing spin coating while irradiating ultraviolet rays. In this case, it is preferable to perform spin coating while performing ultraviolet irradiation through a film thickness distribution adjusting light-shielding mask having an appropriate opening size. By using a light-shielding mask designed to irradiate more ultraviolet rays toward the inner circumference side as the light-shielding mask for film thickness distribution adjustment, the inner circumference tends to be cured before the outer circumference, and the uniformity of the film thickness of the intermediate layer can be improved.

The amount of ultraviolet light and the irradiation time in this step may be appropriately optimized depending on the material of the ultraviolet curable resin raw material and the production environment, and is usually 10mW/cm²～120mW/cm²About 0.1 to 5.0 seconds.

(6) Other steps

In actual production of the optical recording medium, the first to fourth steps are sequentially performed, and after the fourth step, the radiation transmissive stamper 110 is peeled off from the resin material layer 104a (see fig. 1 (c)). Thereby, the intermediate layer 104 is formed after the transfer concave-convex shape of the radiation transmissive stamper 110 is transferred to the resin material layer 104 a. In the present specification, the resin material layer 104a is a layer which is cured after coating and before the radiation transmissive stamper is peeled off. The intermediate layer 104 is a layer from which the radiation transmissive stamper 110 is peeled. Therefore, the resin material layer 104a and the intermediate layer 104 are layers formed at the same position, but the states thereof are different.

The specific method of peeling the radiation transmissive stamper 110 is not limited, and peeling is generally performed by a method of: that is, the inner periphery is vacuum-sucked, the blade edge is caused to enter the central hole side of the optical recording medium, and the data substrate 111 on which the resin material layer 104a is formed and the radiation transmissive stamper 110 are separated while blowing air thereto.

Here, the above-described peeling of the radiation transmissive stamper 110 may be performed at normal temperature or the like without performing temperature control, or may be performed in a state where the data substrate 111 on which the resin material layer 104a is formed is heated, and if the radiation transmissive stamper 110 is peeled in a heated state, the peeling may be performed favorably, the resin material layer 104a having favorable irregularities can be obtained, and further the intermediate layer 104 having favorable irregularities can be obtained, which is a preferable embodiment.

The time for performing the heating operation is arbitrary, but it is preferable to perform the heating operation in the stamper peeling step after curing the ultraviolet curable resin material 104 a. The temperature at which the radiation transmissive stamper 110 is peeled off is arbitrary, but is preferably 50 ℃ or higher in general, and is preferably not higher than the glass transition temperature of the resin material layer 104a (i.e., of the intermediate layer 104) and not higher than the glass transition temperature of the stamper 110.

In the embodiment of the present invention, it is preferable that after the intermediate layer 104 is formed by peeling off the radiation transmissive stamper 110, the intermediate layer 104 is further subjected to a surface modification treatment. Thereby, the intermediate layer 104 is further cured, and stable unevenness is maintained.

Here, the surface modification treatment is not limited as long as it is a treatment for promoting curing of the intermediate layer 104, but a radiation irradiation treatment and/or a heating treatment is preferable. In addition, ultraviolet rays are preferably used as the radiation. Therefore, for example, when the resin material layer 104a is made of an ultraviolet-curable resin material, any of ultraviolet irradiation and heating treatment can be used as the surface modification treatment, but it is preferable to use at least ultraviolet irradiation.

In the above-described specific description of the first step, second step, third step, fourth step, and other steps, the case where the radiation curable resin material is an ultraviolet curable resin material is described, but in the case where the electron beam curable resin material and other radiation curable resin materials are used, the steps are basically substantially the same as those of the first step, second step, third step, fourth step, and other steps using an ultraviolet curable resin material.

(concerning the radiation transmissive stamper)

The "radiation transmissivity" of the radiation transmissive stamper 110 used in the embodiment of the present invention refers to transmissivity to radiation when the radiation curable resin material is cured. Specifically, the radiation has a transmittance of usually 30% or more, preferably 50% or more, and more preferably 60% or more. On the other hand, the transmittance of the radiation is preferably 100%, but is usually 99.9% or less.

In the present invention, "radiation" is used in the meaning including electron beam, ultraviolet ray, visible light, and infrared ray. In the above embodiment, the case where ultraviolet rays are used as radiation has been described as an example, but the present invention is not limited to this.

As the radiation transmissive stamper, a stamper produced by a conventionally known material and a conventionally known production method can be suitably used. As the material of the radiation transmissive stamper, for example, a nonpolar material such as a polyolefin resin or a polystyrene resin, or a general-purpose and low-cost resin such as a polycarbonate resin or an acrylic resin can be used. The radiation transmissive stamper may be made of one kind of material alone, or two or more kinds of materials may be used in combination at an arbitrary combination and ratio.

In the above description, a polycarbonate-based resin which is low in cost and can realize a groove shape with high accuracy is preferable, and a conventionally known polycarbonate-based resin is preferably used for a substrate of an optical recording medium in particular.

For example, the radiation transmissive stamper can be manufactured by injection molding or the like using a metal stamper (for example, a nickel stamper) having a Negative (Negative) uneven pattern of the transfer uneven shape of the radiation transmissive stamper.

The radiation transmissive stamper is generally formed in a disk shape having a central hole penetrating the front surface and the back surface at the central portion. In the embodiment of the present invention, the radiation transmissive stamper is preferably a disk-shaped stamper having a surface with an uneven shape for transfer and a center hole formed in a central portion.

The radiation transmissive stamper used in the embodiment of the present invention is preferably 0.3mm or more in thickness in general from the viewpoint of shape stability and ease of handling. However, it is usually 5mm or less. Since the radiation-transmitting stamper has sufficient radiation transmittance if the thickness thereof is within this range, the ultraviolet-curable resin material can be effectively cured even when the stamper is irradiated with radiation through the radiation-transmitting stamper, thereby improving productivity.

Further, the outer diameter of the radiation transmissive stamper is preferably larger than the outer diameter of the 1 st substrate (i.e., the outer diameter of the optical recording medium). If the outer diameter of the radiation transmissive stamper is designed to be larger than the outer diameter of the 1 st substrate in advance, it is possible to form a concave-convex shape with a margin even in the outer peripheral portion outside the outer diameter of the optical recording medium at the time of injection molding, and it is possible to form a good concave-convex shape along the entire surface of the region used at the time of forming the intermediate layer of the radiation transmissive stamper.

In addition, by making the outer diameter of the radiation transmissive stamper larger than the outer diameter of the 1 st substrate, the outer diameter of the radiation transmissive stamper is larger than the outer diameter of the intermediate layer (i.e., the layer composed of the radiation curable resin raw material). This facilitates the formation of a favorable shape of the end face of the intermediate layer. Specifically, when the radiation transmissive stamper is placed on the radiation curable resin raw material, the resin of the radiation curable resin raw material layer sometimes adheres to the outer peripheral end portions of the radiation transmissive stamper and the intermediate layer, and this resin sometimes becomes burrs when the radiation transmissive stamper is peeled off. Therefore, by making the outer diameter of the radiation transmissive stamper larger than the outer diameter of the intermediate layer (radiation curable resin raw material layer), the resin that is likely to become burrs is positioned outside the outer diameter of the intermediate layer, that is, at the outer peripheral end portion of the radiation transmissive stamper. As a result, even if the burr is generated, the end face of the intermediate layer is not affected, and the portion where the burr is generated can be removed.

Specifically, the outer diameter of the radiation transmissive stamper is preferably 1mm or more, more preferably 2mm or more larger than the outer diameter of the 1 st substrate in general. However, the difference between the diameter and the outer diameter of the 1 st substrate is usually 15mm or less, preferably 10mm or less.

(raw Material for radiation-curable resin)

The radiation-curable resin material used for forming the intermediate layer is not particularly limited as long as it contains a radiation-curable resin that is cured by radiation. The radiation curable resin may be used alone, or two or more kinds may be used together in any combination and ratio.

Examples of the radiation curable resin include various resins such as an ultraviolet curable resin and an electron beam curable resin, and among them, an ultraviolet curable resin is particularly preferable. By using the ultraviolet curable resin, the transfer of the uneven shape of the radiation transmissive stamper is easily performed.

Examples of the ultraviolet-curable resin include radical-type (i.e., radical-polymerization-type) ultraviolet-curable resins and cationic (i.e., cationic-polymerization-type) ultraviolet-curable resins, and conventionally known materials thereof can be suitably used.

When the radical type ultraviolet curable resin is used as the radiation curable resin material, for example, a composition containing an ultraviolet curable compound (radical type ultraviolet curable compound) and a photopolymerization initiator as essential components can be used. As the radical type ultraviolet curable compound, for example, monofunctional (meth) acrylate and polyfunctional (meth) acrylate can be used as the polymerizable monomer component. These may be used alone or in combination of two or more in any combination and ratio. In addition, the acrylate and the methacrylate are collectively referred to herein as (meth) acrylate.

The photopolymerization initiator is not limited, and for example, a molecular cleavage type photopolymerization initiator or a hydrogen abstraction type photopolymerization initiator is preferable. In the present invention, it is preferable to obtain the intermediate layer by curing an uncured ultraviolet-curable resin material mainly composed of a radical-polymerizable acrylic ester.

On the other hand, when a cationic ultraviolet-curable resin is used as the radiation-curable resin material, for example, an epoxy resin including a cationic polymerization type photoinitiator can be used.

Examples of the epoxy resin include bisphenol a-epichlorohydrin type, alicyclic epoxy resin, long-chain aliphatic type, brominated epoxy resin, glycidyl oil type, glycidyl ether type, heterocyclic type and the like. The epoxy resin is preferably an epoxy resin having a low content of free chlorine and chloride ions. The amount of chlorine is preferably 1% by weight or less, more preferably 0.5% by weight or less.

Examples of the cationic polymerization type photoinitiator include sulfonium salts, iodonium salts, and diazonium salts.

The radiation-curable resin material is preferably a resin material that is liquid at 20 to 40 ℃. When a radiation-curable resin material is coated, the coating can be performed without using a solvent, and thus productivity is improved. The radiation-curable resin material is preferably adjusted to have a viscosity of 50cP or more and 1000cP or less at room temperature. More preferably 100cP or more. Further, 500cP or less is more preferable, and 400cP or less is particularly preferable. The viscosity of the radiation-curable resin material can be adjusted by appropriately changing the content of the monomer in the radiation-curable resin material.

B. Another preferred embodiment of the method for producing an optical recording medium of the present invention

The method for manufacturing the optical recording medium of the present invention has been described above by taking a single-sided 2-layer DVD-R or a single-sided 2-layer DVD recordable optical disc as an example, but the present invention is not limited thereto. That is, the effects of the present invention can be exhibited favorably as long as the optical recording medium or the laminated body for an optical recording medium is produced by a production method including the steps of: the intermediate layer is formed by applying a radiation-curable resin material directly on the data substrate or through another layer, fixing a radiation-transmissive stamper having an uneven shape, and then peeling off the stamper, thereby transferring the uneven shape of the radiation-transmissive stamper to the resin. That is, the manufacturing method according to the embodiment of the present invention can be applied to optical recording media having other structures.

For example, the present invention can be applied to an optical recording medium having 3 or more recording layers and 2 or more intermediate layers. In this case, 2 or more intermediate layers can be formed by the manufacturing method according to the embodiment of the present invention. In the above-described embodiments, the method for manufacturing a so-called substrate surface incident type optical recording medium is described, but it is needless to say that the method can be applied to a method for manufacturing a so-called film surface incident type optical recording medium.

Another example of the optical recording medium to which the embodiment of the present invention is applied is a blu-ray disc, and for example, a 2-layer BD-R optical recording medium having a laminated structure in which 2 (dual) recording layers are provided on 1 optical recording medium is cited. Of course, the above-described method for forming the intermediate layer can be applied to a 2-layer BD-R optical recording medium as well. In this case, a protective layer having a thickness of about 75 μm is formed instead of the adhesive layer 107 and the 2 nd substrate 108 described above. As a method for forming the protective layer, a conventionally known manufacturing method such as spin coating can be used. In this case, the 2-layer BD-R optical recording medium is required to have an intermediate layer thickness of about 25 μm in terms of the standard. When the recording layer is 3 or more layers, the thickness of the intermediate layer is appropriately set.

In a film surface incidence type optical recording medium such as BD-R, which is irradiated with a laser beam from the protective layer side, the order of stacking the 1 st recording layer and the 1 st reflective layer and the order of stacking the 2 nd recording layer and the 2 nd reflective layer are reverse to the above-described order, respectively.

In the above-described embodiment, the intermediate layer is a layer consisting of only 1 layer, but in order to improve the releasability of the radiation transmissive stamper from the intermediate layer, it is also possible to adopt a method in which: two or more resin materials are used as radiation curable resin materials for forming the intermediate layer, and the intermediate layer has a laminated structure of different resins. This method has an advantage that, for example, the resin material a having good releasability from the radiation transmissive stamper is used on the radiation transmissive stamper side, and the resin material B having good adhesiveness to the data substrate is used on the data substrate side, whereby the releasability can be improved. In this case, the effect of the present invention can be obtained by applying the manufacturing method of the present invention to only one resin material having a large film thickness of the intermediate layer. Specifically, for example, such examples are listed as follows: the production method of the present invention is employed when a resin material layer made of the resin material B is formed by applying the resin material a to a radiation transmissive stamper in advance and curing the same.

The recording layer material is not particularly limited as long as it can be used for a general optical recording medium, and the production method according to the embodiment of the present invention can be employed. For example, not only the organic pigment material but also a phase change type recording material, a partial nitride film, or a partial oxide film can be used. As a specific example of the phase change type recording material, for example, a composition containing Sb as a main component, such as sbtes, gesbtes, insbtes, agsbtes, aginsbtes, GeSbSn, ingesbtes, and ingesbsntes, is preferably used. Specific examples of the partial nitride film and the partial oxide film include a partial nitride film such as BiGeN and SnNbN, and a partial oxide film such as TeOx and BiFOx.

C. Preferred embodiment of the apparatus for manufacturing an optical recording medium of the present invention

The above-described method for manufacturing an optical recording medium is performed by the following manufacturing apparatus and the like.

Specifically, an optical recording medium has a plurality of recording layers on a disk-shaped substrate having a center hole, and an intermediate layer having a concavo-convex shape made of a radiation-curable resin material is provided between the plurality of recording layers, and an apparatus for manufacturing an optical recording medium is used in a step of forming the intermediate layer, and includes at least the following first unit, second unit, third unit, and fourth unit.

(1) First unit

The first unit of the manufacturing apparatus of the optical recording medium of the present invention is a unit that: a radiation curable resin material is applied between a radiation transmissive stamper and a substrate having the recording layer, so that the radiation transmissive stamper and the substrate having the recording layer are superposed.

Fig. 5 (a) shows an example of the first unit. As shown in fig. 5 (a), the first unit has at least: a substrate holding table section 201 that holds the recording layer side of the data substrate 111 on which the recording layer is formed substantially horizontally as an upper surface and rotates the same, or the like; a stamper holding inversion table section 202 that holds and rotates the radiation transmissive stamper 110 so that the uneven surface side of the radiation transmissive stamper 110 is on the data substrate 111 side; and a nozzle portion 203 that applies the ultraviolet curable resin material 104a between the data substrate 111 and the radiation transmissive stamper 110.

The substrate holding stage 201 includes, for example: a turntable 210 for placing the data substrate 111; a central shaft 211 for inserting the data substrate 111 and the central hole of the radiation transmissive stamper 110; a suction hole 212 for fixing the data substrate 111 so as not to move on the spin base 210; and a rotation mechanism (not shown) for rotating the rotary table 210.

Further, the stamper holding reversal table portion 202 has: an inversion rotation table 214 having a suction hole 213 that holds the radiation transmissive stamper 110 by suction; a conveying mechanism (not shown) capable of conveying the radiation transmissive stamper 110 held by the reverse rotation table 214 in an arbitrary direction; and a rotating mechanism (not shown) for rotating the reversing rotary table 214.

The nozzle section 203 includes a nozzle, a moving mechanism (not shown) for moving the tip of the nozzle to an arbitrary position, a control mechanism (not shown) for discharging a predetermined amount of the ultraviolet curable resin material 104a from the tip of the nozzle, and the like. The number of nozzles for ejecting the ultraviolet curable resin material 104a may be one, or two or more.

In the first unit, for example, as shown in fig. 5 (a), the data substrate 111 and the radiation transmissive stamper 110 are conveyed by the substrate holding table section 201 and the stamper holding turntable section 202, respectively, and are arranged so as to pass through the same central axis 211 and face each other. Then, the tip of the nozzle section 203 is inserted between the two substrates 110 and 111, and a predetermined amount of the ultraviolet curable resin material 104a is discharged from the nozzle section 203. At this time, the turntable 210 of the substrate holding stage 201 and/or the inverting turntable 214 of the stamper holding turntable 202 are/is rotated in the circumferential direction of the data substrate 111, and thereby the ultraviolet curable resin material 104a is applied in an annular shape. After the ultraviolet curable resin material 104a is applied, the nozzle tip is retracted, and both or either one of the turntable 210 and the reverse turntable 214 is moved upward or downward, whereby the data substrate 111 and the radiation transmissive stamper 110 are superposed on each other.

The production conditions such as the amount of application of the ultraviolet-curable resin material 104a in the present unit, and the materials of the ultraviolet-curable resin material 104a, the radiation-transmissive stamper 110, the data substrate 111, and the like used in the present unit can be the same as the production conditions and materials described in the above-described method for producing an optical recording medium.

(2) Second unit

The second unit is a unit that twists the radiation transmissive stamper and the substrate having the recording layer in a state of being pressed in a direction of bringing the substrates close to each other, even if the substrates rotate relative to each other, thereby extending the radiation curable resin material

In the second unit, as shown in fig. 5 (b), for example, the turntable 210 of the substrate holding table section 201 and/or the inverting turntable 214 of the stamper holding turntable section 202 described above are moved upward or downward, the data substrate 111 and the radiation transmissive stamper 110 are pressurized in a direction to approach each other, and both or either one of the turntable 210 and the inverting turntable 214 is rotated in the circumferential direction of the data substrate 111, whereby the ultraviolet curable resin material 104a applied by the first unit is extended on both substrate surfaces.

In the second unit, the pressurized state may be controlled by fixing one of the turntable 210 and the reversing turntable 214 and moving the other one upward or downward, or the pressurized state may be controlled by moving both the turntable 210 and the reversing turntable 214 upward and downward.

In addition, when the radiation transmissive stamper 110 and the data substrate 111 are twisted, the rotation of each of the turntable 210 and the inversion turntable 214 may be controlled so that one is fixed and the other is rotated in the circumferential direction, or the rotation of the radiation transmissive stamper 110 and the data substrate 111 in the opposite direction may be controlled so that the turntable 210 and the inversion turntable 214 are rotated in the opposite direction.

After the rotation, the stamper holding rotary table section 202 is detached from the radiation transmissive stamper 110, and the radiation transmissive stamper 110 is held on the substrate holding table section 201 side in a state of being overlapped with the data substrate 111.

The manufacturing conditions such as the pressing width at the time of the pressure control, the rotation speed at the time of the twisting, and the rotation angle can be the same as the manufacturing conditions described in the above-described method for manufacturing the optical recording medium.

(3) Third unit

The third unit is a unit for irradiating radiation only to the vicinity of the center hole of the substrate and curing the radiation curable resin material.

For example, as shown in fig. 5 (c), the third unit is a unit having a radiation source 205 for radiating radiation 220, and a light shielding mechanism 204 capable of shielding a target region from light.

Further, the third unit preferably has a pressing mechanism for pressing the center hole side of the radiation transmissive stamper 110, and the pressing mechanism may also serve as a light shielding mechanism.

The radiation source 205 used in the third unit is not particularly limited as long as it can irradiate radiation 220 capable of curing the ultraviolet-curable resin material 104a at a predetermined timing, and can be appropriately selected according to the type of the ultraviolet-curable resin material 104a, the required intensity, and the like.

The light shielding mechanism is, for example, a light shielding mechanism including a light shielding mask, a light shielding mask conveying mechanism capable of conveying the light shielding mask to an arbitrary position, and the like.

Fig. 5 (c) shows a mode in which the pressing mechanism doubles as the light shielding mechanism 204. The pressing mechanism has one or more hammers (indicated by fingers 204a to 204c in fig. 5 c) and a hammer conveyance mechanism 204d, and the hammer conveyance mechanism 204d supports the hammers 204a to 204c and can convey them to arbitrary positions on the radiation transmissive stamper 110.

For example, the weight 204a disposed in the region irradiated with radiation is made of a material having radiation transmittance, and the weights 204b and 204c disposed in the regions not irradiated with radiation are made of a material having light shielding properties, whereby pressurization and light shielding can be performed simultaneously by the weights.

As shown in fig. 5 c, the third unit may further include a suction mechanism (not shown) for performing reduced pressure suction of the radiation curable resin material 104a from the central axis 211 of the substrate holder 201. When the suction mechanism is provided, the radiation-curable resin material 104a can be extended to the central hole side of the data substrate 111 as soon as possible before or during the radiation irradiation from the radiation source 205, and the tact time and the like can be shortened.

After the radiation irradiation, the light shielding mechanism 204 and the like are removed from the radiation transmissive stamper.

The production conditions such as the radiation irradiation amount and irradiation time from the radiation source, the pressurization amount, and the suction pressure of the suction mechanism in the present unit can be the same as those described in the above-described method for producing an optical recording medium.

(4) Fourth unit

A fourth unit is a unit that, in order to extend the radiation curable resin material to the entire substrate having the recording layer, cures the radiation curable resin material extending to the entire substrate while performing rotation of the substrate having the recording layer and the radiation transmissive stamper, and bonds the radiation transmissive stamper and the substrate having the recording layer.

The fourth unit is, for example, a unit having the following parts as shown in fig. 5 (c): a rotation mechanism (not shown) that rotates the turntable 210 and simultaneously rotates the data substrate 111 and the radiation transmissive stamper 110 at a high speed; and a radiation source 206 that irradiates radiation 220 for curing the radiation curable resin material 104a while rotating. In this embodiment, the rotation mechanism and the radiation source 206 are preferably controlled so that the irradiation of the radiation 220 from the radiation source 206 is started substantially simultaneously with the start of the rotation mechanism and the irradiation is ended substantially simultaneously with the end of the rotation.

The radiation source 206 may be the same as the third unit, or may be a different radiation source.

In the present invention, it is preferable that the fourth unit further includes a light shielding mechanism (not shown) in addition to the above-described rotation mechanism and the radiation source. The radiation curable resin material 104a is generally stretched by simply rotating the rotation mechanism, so that the inner periphery is thin and the outer periphery is thick. Therefore, by irradiating ultraviolet rays through a light-shielding mask having an opening whose irradiation amount is changed in accordance with the radius and rotating the mask at a high speed, and sequentially curing the mask from the center hole side in the high-speed rotation process, a film thickness that is substantially uniform over the entire surface can be formed. Such a light shielding mechanism can be realized as a light shielding mechanism including a light shielding mask capable of adjusting the dose of radiation from the radiation source 206, a light shielding mask conveying mechanism capable of conveying the light shielding mask to an arbitrary position, or the like.

The manufacturing conditions such as the rotational speed of the rotating mechanism and the irradiation of radiation from the radiation source in the present unit can be the same as those described in the above-described method for manufacturing an optical recording medium.

(5) Others

In the above-described embodiment, the same substrate holder 201 is used for the first to fourth units, but different substrate holders 201 may be used for these units. Further, the description has been made with the radiation transmissive stamper 110 on the upper side and the data substrate 111 on the lower side, but the units may be arranged upside down on the two substrates. The present invention is not limited to the above configuration, and may have other configurations as needed.

Examples

The present invention will be described in more detail with reference to the following examples, which are not intended to limit the scope of the present invention.

(example 1)

Example 1 shows an example of manufacturing an additionally written 2-layer blu-ray disc using the method of the present invention.

An additional write-type recording film made of an inorganic film (hereinafter, a substrate having a recording film formed on a polycarbonate substrate as described above is referred to as a "data substrate") was formed on the surface of a polycarbonate substrate obtained by injection molding through a plurality of sputtering film forming steps, and grooves having a track pitch of 0.32 μm and a depth of 20nm were transferred onto the surface of the polycarbonate substrate, and the thickness of the polycarbonate substrate was 1.1mm and the diameter was 120 mm. By injection molding in a manner different from this, a polycarbonate substrate having a thickness of 0.6mm and a diameter of 124mm, on the surface of which grooves having a pitch of 0.32 μm and a depth of 20nm were transferred (hereinafter, the polycarbonate substrate having the grooves formed thereon will be referred to as a "radiation transmissive stamper") was produced. The grooves of the data substrate surface and the grooves of the radiation transmissive stamper surface were grooves in which the orientation of the irregularities of the grooves of the nickel stamper used in injection molding was reversed, thereby forming reverse orientations of the irregularities.

The data substrate and the radiation transmissive stamper each had a center hole with a diameter of 15mm formed at the center thereof, and a small annular projection 300 having a height of about 15 μm was formed in advance by injection molding at a position of 20mm in diameter around the center of the data substrate and the radiation transmissive stamper as shown in fig. 4.

Then, the radiation transmissive stamper is fixed to a rotation capable of rotating at a high speedOn the stage, an ultraviolet-curable resin material A having a viscosity of about 280cP at normal temperature (hereinafter, simply referred to as "resin A") was annularly applied to a position of a radius of 166mm on the radiation-transmissive stamper using a nozzle having an outer diameter of 1.08mm and an inner diameter of 0.72mm at the tip. The coating amount was about 3 g. The high-speed rotation was started when the resin A naturally sufficiently reached the small projection having a diameter of 20mm on the radiation transmissive stamper after several seconds, and after rotating at 9100rpm for 4 seconds, the atmosphere above the radiation transmissive stamper was purged with nitrogen gas and irradiated with 70mW/cm²The ultraviolet ray (2) for 1 second, the resin A was cured. The thickness of the cured film of the resin A at this time was about 10 μm.

Then, the radiation transmissive stamper on which the cured film of the resin a was formed and the data substrate were fixed on another rotary table, and then they were opposed to each other at an interval of 3 mm. The two rotating tables were rotated 1 rotation in synchronization, and about 3g of an ultraviolet-curable resin material B (hereinafter, simply referred to as "resin B") having a viscosity of about 380cP at room temperature was applied to a position of a radius of 30mm from the centers of the radiation-curable transmissive stamper and the data substrate in the gap by using a nozzle having an outer diameter of 1.49mm and an inner diameter of 1.11mm at the tip. At this time, the center hole of the data substrate and the center hole of the radiation transmissive stamper are penetrated through the same center axis, and the eccentricity of the two substrates is adjusted to be within 30 μm.

Then, the turntable of the data substrate was fixed, the interval between the two substrates was reduced by 45 μm, and only the turntable of the radiation transmissive stamper was rotated at 15rpm by 180 ° and twisted to elongate the resin B. Then, the turntable of the radiation transmissive stamper was removed, a quartz ring capable of transmitting ultraviolet rays sufficiently was placed at a position with a radius of 7.5mm to 11mm in a range from the vicinity of the center hole of the radiation transmissive stamper to the circumference of the disk center, and the inner circumference weight and the outer circumference weight were brought into contact with a position with a radius of 11mm to 28mm, and a total load of 80g was applied. Here, the inner peripheral weight and the outer peripheral weight are made of a light-shielding material. The resin B is naturally extended between the two substrates in this state with the small projections on the two substrates facing each other, and just after the inner peripheral side extending end of the resin B reaches the small projection, ultraviolet rays from a high-pressure mercury lamp are irradiated only to the vicinity of the center hole from above the radiation transmissive stamper. Here, the inner peripheral weight functions as a light-shielding mask, and irradiates ultraviolet light only in a circular region having a radius of 11mm or less. In this case, in addition to the natural extension toward the inner peripheral side, the resin is sucked under reduced pressure at a pressure of-12 kPa from the fine holes for suction under reduced pressure provided on the side surface of the central axis passing through the central holes of the two substrates, whereby the time required for the inner peripheral side extension end of the resin to reach the projection can be shortened.

The amount of ultraviolet light at this time was 70mW/cm²The irradiation time was 1 second. Although the appropriate irradiation amount depends on the curing property of the resin B and the light transmittance of the cured film of the resin a and the radiation transmissive stamper, the irradiation amount is set to a degree that the resin B in the irradiation range is completely cured.

Then, the hammers and the quartz ring were removed, and the two substrates were fixed to a turntable and rotated at high speed to stretch the resin B. At this time, the rotation speed was 7800rpm so that the thickness of the intermediate layer between the two substrates became the desired film thickness, here, a thickness of about 25 μm.

Since the thickness of the resin material is usually reduced at the inner periphery and increased at the outer periphery by simply performing the rotational stretching, the ultraviolet rays are irradiated through the light-shielding mask having the opening whose irradiation amount is changed according to the radius, and the resin material is rotated at high speed, and is sequentially cured from the inner periphery side in the high-speed rotation process, whereby a film thickness which is substantially uniform over the entire surface can be formed. The irradiation with ultraviolet rays for film thickness adjustment is performed by starting the irradiation substantially at the same time as the start of rotation and ending the irradiation substantially at the same time as the end of rotation.

By appropriately adjusting the shape of the light-shielding mask and the ultraviolet irradiation intensity in accordance with the curability of the resin B and the ultraviolet transmittance of the cured film of the resin a, it is possible to suppress the variation in the film thickness of the intermediate layer to about 2 μm (maximum film thickness-minimum film thickness) over the entire disk recording region. There is no problem that air enters from the inner peripheral end of the cured film of the resin B having a diameter of 20mm to separate the substrates from each other or air bubbles enter from the inner peripheral end of the resin in the period from the cutoff to the end of the rotation.

After the high-speed rotation is stopped, the entire surface of the substrate is continuously irradiated with ultraviolet rays from the radiation transmissive stamper side to completely cure the resin B, and the radiation transmissive stamper and the cured film of the resin a are peeled off by a mechanical force. When a resin material having good releasability from polycarbonate is used as the resin a and a resin material having good adhesive property to polycarbonate is used as the resin B, the radiation-transmissive stamper and the resin a can be peeled from each other when the two substrates are peeled from each other by a mechanical force.

On the substrate obtained by laminating the data substrate thus obtained, resin B and resin a in this order, an additional write-type recording film was laminated by a plurality of sputtering steps, and then an ultraviolet curable resin C was spin-coated, thereby forming a protective layer having a thickness of about 75 μm. In this case, it is necessary to form a uniform protective layer from the portion having a diameter of 23mm corresponding to the inner peripheral end of the disk clamping portion, but by forming the intermediate layer in this region in a substantially uniform state as described above, a uniform protective layer can be formed when the resin C is applied, and air bubbles are not entrained.

The servo characteristics of the optical recording medium of example 1 of the present invention obtained through the above procedure were evaluated, and the results are shown in table 1. Servo characteristics were evaluated by evaluating servo residues (サーボ residues) when recording and reproducing data on and from the 2 nd recording layer formed on the intermediate layer. When recording and reproducing data, it is necessary to move an objective lens of an optical pickup up and down automatically so that a focal point of a recording and reproducing laser beam follows a recording surface. The servo residual is an index indicating a moving distance of the objective lens at the time of automatic tracking, and if the servo residual is too large at the time of recording and reproducing on and from the optical recording medium, a servo failure occurs, resulting in a recording and reproducing error. The value of the servo residual of the blu-ray disc is preferably 45nm or less in 2 x speed recording and 80nm in 4 x speed recording.

In the present invention, the servo residuals are calculated from the driving voltage required to cause the objective lens of the optical pickup to automatically follow the recording/reproducing operation, and the values of the servo residuals at each radius from the inner periphery to the outer periphery are evaluated at the 2 × speed and the 4 × speed.

As shown in table 1, in example 1, values of less than 45nm were obtained for the 2 × speed and values of less than 80nm were obtained for the 4 × speed over the entire surface of the optical recording medium, and good servo characteristics were obtained. This indicates that the uniformity of the film thickness of the intermediate layer is good, and thus the objective lens can sufficiently follow.

Comparative example 1

An optical recording medium was produced in the same manner as in example 1 except that no twisting was performed, and the servo residue was evaluated, and the results are shown in table 2. Although a value of less than 45nm was obtained at 2 times speed, a value exceeding 80mm was obtained at the inner peripheral side at 4 times speed. This is understood to mean that since no twisting is performed, the film thickness uniformity of the intermediate layer on the inner peripheral side is deteriorated.

Comparative example 2

An optical recording medium was produced in the same manner as in example 1 except that the inner periphery curing was not performed, and in the case where the inner periphery curing was not performed, air entered the intermediate layer from the inner periphery at the time of high-speed stretching in the fourth step, so that the above radiation transmissive stamper was peeled off, and the production of the optical recording medium was difficult.

In view of the above, the method for manufacturing an optical recording medium of the present invention can form a more uniform intermediate layer, and can manufacture an optical recording medium having good servo characteristics even when the 2 nd recording layer on the intermediate layer is recorded at high speed.

[ Table 1]

[ Table 2]

Industrial applicability

The present invention is applicable to a method for manufacturing a two-layer optical recording medium having 2 recording layers including an intermediate layer having uniform optical characteristics over the entire surface. The present invention is also applicable to improving the manufacturing efficiency of a laminated multilayer optical recording medium by the 2P method.

In addition, the present invention incorporates the entire contents of the specification, claims, drawings and abstract of japanese patent application No. 2010-090810, filed 4/9/2010, and serves as the disclosure of the present invention.

Description of the reference symbols

100 optical recording media; 101 a 1 st substrate; 102 a 1 st recording layer; 103 a 1 st reflective layer; 104a an ultraviolet-curable resin material, a resin material layer; 104 an intermediate layer; 105 a 2 nd recording layer; 106 a 2 nd reflective layer; 107 an adhesive layer; 108 a 1 st substrate; 109 a laser beam; a 110 radiation transmissive stamper; 111 a data substrate; 120 quartz ring (hammer); 121. 122 light-blocking hammer; 123 central axis; 124 pores; 201 a substrate holding table portion; 202 a stamper holding the inverted stage portion; 203 a nozzle part; 204a light shielding mechanism; 204a, 204b, 204 c; 204d hammer conveying mechanism; 205. 206 a radiation source; 210 a rotating table; 211 a central axis; 212. 213 suction holes; 214 reversing the rotary table; 220 radioactive rays; 300 small protrusions.

Claims (10)

1. A method for manufacturing an optical recording medium having a plurality of recording layers on a disk-shaped substrate having a center hole, an intermediate layer formed of a radiation-curable resin material and having a concave-convex shape between the plurality of recording layers,

the step of forming the intermediate layer at least includes, in the following order:

a first step of applying the radiation curable resin raw material between a radiation transmissive stamper and a substrate having the recording layer so that the radiation transmissive stamper and the substrate having the recording layer are overlapped;

a second step of twisting the radiation transmissive stamper and the substrate having the recording layer in a state of being pressed in a direction of approaching each other, thereby extending the radiation curable resin material;

a third step of irradiating the vicinity of the center hole of the substrate with radiation to cure the radiation-curable resin material; and

a fourth step of curing the radiation curable resin raw material extending to the entire substrate having the recording layer while performing rotation of the substrate having the recording layer and the radiation transmissive stamper, in order to extend the radiation curable resin raw material to the entire substrate having the recording layer, and bonding the radiation transmissive stamper and the substrate having the recording layer.

2. A method of manufacturing an optical recording medium according to claim 1, wherein the substrate and the radiation transmissive stamper are each formed with a small annular projection at: the face side overlapped in the first step is positioned closer to the center hole side than the chucking region.

3. The method of manufacturing an optical recording medium according to claim 1 or 2, wherein the second step includes a twisting step of relatively rotating the radiation transmissive stamper and the substrate having the recording layer, the rotation speed of the twist in the twisting step is set to 0.1rpm to 30rpm, the pressing width between twists is set to 10 μm to 100 μm, and the rotation angle of the twist is set to a range of 180 ° to 360 °.

4. A method for manufacturing an optical recording medium according to any one of claims 1 to 3, wherein in the third step, a range of irradiation with the radiation is set to a range within 15mm of a radius from a center of the substrate.

5. A method for manufacturing an optical recording medium according to any one of claims 1 to 4, comprising, between the second step and the third step, the step of: the pressing is performed by applying a load of 50g to 100g between the radiation transmissive stamper and the substrate.

6. A method for manufacturing an optical recording medium according to any one of claims 1 to 5, comprising, between the second step and the third step, the step of: the radiation curable resin material is subjected to reduced pressure suction from a central axis for fixing the radiation transmissive stamper and the central hole of the substrate.

7. A method for manufacturing an optical recording medium according to any one of claims 1 to 6, wherein the viscosity of the radiation curable resin material is between 50cP and 1000 cP.

8. A method for manufacturing an optical recording medium according to any one of claims 2 to 7, wherein a total height of the small projection of the radiation transmissive stamper and the small projection of the substrate is within ± 15 μm of a target film thickness of the intermediate layer, and a radial misalignment between the small projection of the radiation transmissive stamper and the small projection of the substrate is within 0.5 mm.

9. A method for manufacturing an optical recording medium according to any one of claims 6 to 8, wherein a suction pressure in the step of performing reduced pressure suction of the radiation curable resin material from the central axis is in a range of-1 kPa to-20 kPa.

10. An apparatus for manufacturing an optical recording medium having a plurality of recording layers on a disk-shaped substrate having a center hole, an intermediate layer formed of a radiation curable resin material and having a concave-convex shape between the plurality of recording layers, the apparatus comprising at least:

a first unit that applies the radiation curable resin raw material between a radiation transmissive stamper and a substrate having the recording layer so that the radiation transmissive stamper and the substrate having the recording layer are overlapped;

a second unit that twists the radiation transmissive stamper and the substrate having the recording layer in a state of being pressed in a direction of approaching each other, thereby extending the radiation curable resin material;

a third unit that cures the radiation-curable resin material by irradiating radiation only in the vicinity of the center hole of the substrate; and

a fourth unit that cures the radiation curable resin material extending over the entire substrate having the recording layer while performing rotation of the substrate having the recording layer and the radiation transmissive stamper, and bonds the radiation transmissive stamper and the substrate having the recording layer.