JP2008186509A - Optical information recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for forming a guide groove, a recording layer and a reflection layer, on the side of a thin resin substrate whose mechanical strength is comparatively weak. <P>SOLUTION: The resin substrate 32 is constituted so that a second substrate 3 which has a through hole CH with diameter of 15 mm at a center part, and has 0.1 mm thickness and 120 mm diameter is held by a ring-shaped frame 33 of 0.3 to 0.6 mm in thickness. The ring-shaped frame 33 serves as a reinforcing member. The second substrate 3 is held by devices via the ring-shaped frame 33 upon conveyance to subsequent processes or spin coat. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a next-generation optical information recording medium such as a BD-R (recordable Blu-ray disc) and a method for manufacturing the same.

  As information recording media, optical information recording media such as optical discs are rapidly spreading. Such an optical information recording medium has a thickness of 1.2 mm and a diameter of 120 mm in which a guide groove (pre-groove) is formed on a surface opposite to the light incident surface side, such as a CD-R (recordable CD). Alternatively, there is one in which a reflective layer and a recording layer are sequentially formed on an 80 mm light-transmitting resin substrate. In recent years, higher information recording density has been demanded. Therefore, in order to reduce the spot diameter and realize high-density recording, a method of using an objective lens with a short laser wavelength and a large numerical aperture (NA) can be considered, for example, DVD ± R (recordable DVD). ) Is realized. This DVD ± R is bonded to two optically transmissive resin substrates having a thickness of 0.6 mm in order to increase the allowable value of the tilt angle (tilt) of the disc by shortening the wavelength and increasing the NA. The reflective layer and the recording layer are sandwiched between them.

  However, in recent years, a higher information recording density has been required in order to record high-definition video data. Therefore, a reflective layer and a recording layer are formed on the light incident side of a resin substrate having a thickness of 1.1 mm as in a BD-R (write-once Blu-ray disc), and on the surface on which the reflective layer and the recording layer are formed. An optical information recording medium having a structure provided with a light-transmitting cover layer having a thickness of 0.1 mm has been proposed.

Such an optical information recording medium 1 ′ is, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-45079, as shown in FIG. 11, a first 1.1 mm thick guide groove GV ′ formed on the light incident surface side. A reflective layer 5 ′ and a recording layer 4 ′ are sequentially formed on the substrate 2 ′, and a light-transmissive resin second substrate 3 ′ having a thickness of 0.1 mm is provided thereon. It is formed in the same size as DVD ± R. Further, in Japanese Patent Laid-Open No. 2003-36562, as shown in FIG. 11, in order to protect the recording layer 4 ′, further light transmission is provided between the recording layer 4 ′ and the second substrate 3 ′. A protective layer 7 made of an inorganic material is provided. Data recording on the optical information recording medium 1 'is performed by irradiating a recording laser from the second substrate 3' side to form pits in the recording layer 4 'in the guide groove GV'. Data reproduction is performed by reading the modulation caused by the difference in light intensity between the pit-formed part and the non-pit-formed part. The magnitude of the modulation depends on the optical path length change in the pit. Depends on the size of

JP 2003-45079 A JP 2003-36562 A

In such an optical information recording medium 1 ′, when forming a light-transmitting second substrate 3 ′ having a thickness of 0.1 mm, the gap between the molds is very narrow in the injection molding. Since it is difficult to mold a 1 mm substrate, a 0.1 mm thick resin sheet is attached with an adhesive, or a curable resin such as an ultraviolet curable resin is applied and cured by a spin coat method or the like, Either method is used. Therefore, it is necessary to form a light-transmitting protective layer 7 made of an inorganic material on the recording layer 4 ′ so that the recording layer 4 ′ is not affected by the adhesive or curable resin of the adhesive layer 6 ′. Further, since the protective layer 7 is formed on the organic dye and the recording laser and the reproduction laser are transmitted, the materials that can be used are limited. Also, an apparatus for forming such a material is very expensive.

Furthermore, in such an optical information recording medium 1 ′, the reflective layer 5 ′ is formed on the first substrate prior to the recording layer 4 ′, but the reflective layer 5 ′ is formed in the guide groove GV ′. The depth of the guide groove GV ′ becomes shallower by the thickness of the reflective layer 5 ′. For example, in the embodiment of Japanese Patent Laid-Open No. 2003-45079, a reflective layer having a thickness of 100 nm is formed in a guide groove having a width of 210 nm and a depth of about 150 nμm (in the case of 3λ / 8 and λ = 405 nm). Filled with layers of metal. When the guide groove GV ′ becomes shallow in this way, the optical path length change in the formed pits cannot be sufficiently obtained, and as a result, sufficient modulation cannot be obtained. In order to avoid this, it is necessary to control the thickness of the reflective layer 5 '. For this reason, the reflective layer 5 'needs to be formed with a very thin film thickness of, for example, 10 to 50 nm. Therefore, it is very difficult to set the film forming conditions, and the film forming apparatus used for this is also highly accurate. It was very expensive because it was required.

Such a problem can be solved by providing a guide groove on the second substrate on the light incident side as in DVD ± R and sequentially forming the recording layer and the reflective layer thereon, but the thickness is 0.1 mm. However, this resin substrate has a relatively low mechanical strength and cannot withstand film formation methods such as spin coating. In addition, it is necessary to use an injection molding method for a resin substrate having a guide groove. However, when a resin substrate having a thickness of 0.1 mm is formed by injection molding, the mold space becomes very narrow. It was difficult. Therefore, it was difficult to form a resin substrate having a thickness of 0.1 mm having guide grooves.

  Therefore, the present invention proposes a means that can form a guide groove, a recording layer, and a reflective layer on a thin resin substrate having relatively low mechanical strength. As a solution, a circular first substrate having a through-hole in the center, and a light-transmissive second substrate that is substantially the same shape as the first substrate and is thinner than the first substrate. The second substrate has a spiral or concentric guide groove on one surface, and a recording layer and a reflective layer are sequentially formed in a region of the second substrate where the guide groove is formed. And manufacturing an optical information recording medium formed by adhering a surface of the second substrate on which the recording layer and the reflective layer are formed and one surface of the first substrate to face each other with an adhesive layer In the method, the step of forming the first substrate by injection molding, and forming an intermediate substrate having a guide groove formed on one surface and thicker than the thickness of the second substrate by injection molding, The surface on the opposite side of the surface on which the guide groove is formed is Forming a precursor substrate in which the second substrate and the ring-shaped frame are integrated by pressing with a pressing member having a circular pressing portion having a diameter equal to or larger than the diameter, and forming the guide groove of the precursor substrate. Forming a recording layer in the region, and then forming a reflective layer; and bonding a surface on one side of the first substrate and a surface of the second substrate on which the recording layer and the reflective layer are formed; And a step of cutting out the second substrate from the precursor substrate so as to have the same shape as the first substrate.

  According to the above solution, a thin resin substrate, which has been difficult for injection molding in the past, can be formed by combining the press with injection molding, so that the guide groove can be formed on the second substrate. become. In addition, a precursor substrate in which the second substrate is held by a ring-shaped frame having a thickness larger than that of the second substrate is formed by the above solution. Thus, a film forming method such as spin coating is performed with the second substrate reinforced. Therefore, the spin coating method can be applied to the second substrate having a relatively weak mechanical strength.

  Further, in the present invention, a circular first substrate having a through-hole in the center, a light-transmissive second substrate that is substantially the same shape as the first substrate and is thinner than the first substrate, The second substrate has a spiral or concentric guide groove on one surface, and a recording layer and a reflective layer are sequentially formed in a region of the second substrate where the guide groove is formed. An optical information recording medium formed by bonding the surface of the second substrate on which the recording layer and the reflective layer are formed and one surface of the first substrate to face each other with an adhesive layer The second substrate has an intermediate substrate having a guide groove formed on one surface thereof by injection molding and thicker than the thickness of the second substrate, and the intermediate substrate has a guide groove formed on the surface thereof. The opposite surface is pushed with a pressing member having a circular pressing portion that is equal to or larger than the diameter of the second substrate. We propose an optical information recording medium, characterized in that is cut out from the scan was formed precursor substrate.

In the optical information recording medium as described above, since the recording layer is formed on the second substrate on the light incident side, it is not necessary to form a protective layer. In addition, since it is not necessary to form a reflective layer in the guide groove, the depth of the guide groove is not reduced by the reflective layer, and a sufficient depth can be ensured.

According to the present invention, since the recording layer can be formed on the second substrate having a relatively low mechanical strength by the spin coating method, it is not necessary to provide a protective layer for protecting the recording layer. In addition, since the reflective layer is not formed in the guide groove, a particularly high accuracy is not required for setting conditions when forming the reflective layer. Therefore, an optical information recording medium can be easily obtained without requiring expensive equipment. In addition, since the reflective layer is not formed in the guide groove, a sufficient depth of the guide groove can be ensured, thereby obtaining an optical information recording medium capable of obtaining sufficient modulation.

An embodiment of the optical information recording medium of the present invention will be described with reference to the drawings, taking BD-R as an example. FIG. 1 is a schematic view showing a part of a cross section of an optical information recording medium of the present invention. Such an optical information recording medium 1 has a 0.1 mm thick second guide groove GV having a width of 0.21 μm and a depth of 0.16 μm formed at a pitch of 0.35 μm or 0.32 μm. A recording layer 4 and a reflective layer 5 are sequentially formed on a substrate 3, and a first substrate having a thickness of 1.1 mm is bonded via an adhesive layer 6.

The first substrate 2 is a resin disc having a diameter of 120 mm and having a through hole having a diameter of 15 mm in the center and a thickness t of 1.1 mm. For the first substrate 2, various materials used as substrate materials for conventional optical information recording media can be arbitrarily selected and used. Specific examples include acrylic resins such as polycarbonate and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, metals such as epoxy resins, amorphous polyolefins, polyester resins, and aluminum, and glass. If necessary, they may be used in combination such as by laminating them. Among the above materials, a thermoplastic resin is preferable from the viewpoint of moldability, moisture resistance, dimensional stability, and low price, and polycarbonate is particularly preferable. Such a first substrate 2 is formed by injection molding.

  The second substrate 3 is a resin disc having a diameter of 120 mm and having a through hole having a diameter of 15 mm in the center and a thickness of 0.1 mm. The second substrate 3 is made of the same material as the first substrate 2 described above, has a thickness of 0.1 mm, and is measured by a spectrophotometer with light having a wavelength of 405 nm, preferably 70% or more, preferably 80 A light transmissive material having a light transmittance of at least% is used, and polycarbonate is particularly preferred. Such a second substrate 3 is formed by injection molding using a method described later. At this time, a stamper is set in the mold, whereby a guide groove GV is formed on the second substrate 3.

  The recording layer 4 is formed of an organic material containing a dye, and is formed by applying a solution of a dye such as an azo dye or a cyanine dye in a TFP (tetrafluoropropanol) solution by a spin coating method. . The reflective layer 5 is formed of a metal thin film having high reflectivity such as Ag or Al, and is formed by sputtering or the like. The adhesive layer 6 is made of an ultraviolet curable resin such as an epoxy adhesive.

  Next, a method for producing the optical information recording medium 1 of the present invention will be described. First, the first substrate 2 is prepared. The first substrate 2 is obtained by injecting polycarbonate into a mold, and is formed into a circular single plate having a diameter of 120 mm, a thickness of 1.1 mm, and a through hole having a diameter of 15 mm in the center. The first substrate 1 is used for thickness adjustment for setting the thickness of the optical information recording medium 1 to 1.2 mm, and a surface opposite to the light incident side is used as a label surface.

  Next, a second substrate 3 is prepared. First, as shown in FIG. 2, the stamper ST is set in the lower mold UK, the upper mold (not shown) is set, polycarbonate is injected into the mold by an injection molding machine, and the diameter is 15 mm in the center. An intermediate substrate 31 having a through hole CH and a thickness greater than 0.1 mm is formed. The diameter is 120 mm or more, for example, about 130 to 150 mm, and the thickness is about 0.3 to 0.6 mm. Here, the upper mold is removed, and the intermediate substrate 31 is taken out while the lower mold UK and the stamper ST are set.

  Subsequently, as shown in FIG. 3, the intermediate substrate 31 is pressed by the pressing member 10 before being cured, and as shown in FIG. 4, a precursor substrate 32 in which a recess having a thickness of 0.1 mm is formed. The pressing member 10 is provided with a pressing portion having a diameter of 120 mm or more, whereby a recess having a diameter L1 of 120 mm or more and a thickness t1 of 0.1 mm is formed. At this time, the press is performed from the opposite side of the surface on which the lower mold UK and the stamper ST are set while the lower mold UK and the stamper ST are set so that the guide groove GV is not crushed by the press. Here, when the intermediate substrate 31 is pressed by the pressing member 10, excess polycarbonate is pushed out to the periphery. The extruded polycarbonate is formed into a ring shape having a thickness t2 of 0.3 to 0.6 mm. The diameter L2 of this ring is preferably 140 to 160 mm.

  In this way, a precursor substrate 32 as shown in FIG. 5 is obtained. This precursor substrate 32 has a through hole CH having a diameter of 15 mm in the center and a second substrate 3 having a thickness of 0.1 mm and a diameter of 120 mm, and a ring-shaped frame having a thickness of 0.3 to 0.6 mm. 33 is held. This ring-shaped frame 33 serves as a reinforcing member. At the time of conveyance to the subsequent processes or at the time of spin coating, the second substrate 3 is held by the apparatus via the ring-shaped frame 33.

  Next, as shown in FIG. 6, a dye solution is applied onto the precursor substrate 32 by a spin coating method to form the recording layer 4. First, the precursor substrate 32 is held via the ring-shaped frame 33 on the fixed member 11 of the rotary table of the spin coater so that the surface on which the guide groove GV is formed is up. Subsequently, the rotary table is rotated at 5000 rpm, and the organic dye solution is discharged from the nozzle and applied. Since the second substrate 3 is reinforced by the ring-shaped frame 33, it can have a sufficient durability against the rotation of the spin coater. Although not shown, the portion of the second substrate 3 may be supported by a method such as suction holding so that the second substrate 3 does not wave during rotation.

  Next, as shown in FIG. 7, an Al metal thin film is deposited on the recording layer 4 by sputtering to form a reflective layer 5. At this time, fixation to the sputter is performed via a ring-shaped frame 33. Since the reflective layer 5 is not formed in the guide groove GV as in the conventional BD-R, the setting of the film forming conditions becomes relatively gradual, and the film forming apparatus used therefor does not require high accuracy. . Therefore, it becomes possible to use the conventional sputtering used for manufacturing CD-R and DVD-R.

  Next, as shown in FIG. 8, the 1st board | substrate 2 and the precursor board | substrate 32 are bonded through the adhesive bond layer 6 which consists of ultraviolet curable resin. At this time, the adhesive layer 6 may be formed by applying an adhesive by spin coating on the precursor substrate 32 side, or by applying an adhesive by spin coating on the first substrate 2 side. . After bonding, the adhesive layer 6 is cured by irradiating with ultraviolet rays.

  Next, as shown in FIG. 9, the ring-shaped frame 33 is removed from the precursor substrate 32 using the cutter 12, and the second substrate 3 is cut out so as to have the same shape as the first substrate 2. The precursor substrate 32 is cut by the cutter 12 while being rotated at 30 to 60 rpm, and the second substrate 3 and the ring-shaped frame 33 are separated. As the cutter 12, a single blade or a rotary cutter can be used. Here, the process of cutting out the second substrate 3 from the precursor substrate 32 is performed after being bonded to the first substrate 2, but may be performed before being bonded to the first substrate 2. That is, after the second substrate 3 is cut out from the precursor substrate 32, the first substrate 2 and the second substrate 3 may be bonded together.

  Through the above process, the optical information recording medium 1 as shown in FIG. 10 is manufactured. In the optical information recording medium 1 obtained in this way, the guide groove GV is not filled with the metal of the reflective layer, so that the guide groove GV can be relatively deep. Therefore, the optical path length change in the pit can be taken sufficiently. As a result, it is possible to obtain the optical information recording medium 1 capable of obtaining sufficient modulation.

  As described above, in the description of the embodiment of the present invention, the case of a single-layer BD-R has been described as an example of conditions such as numerical values, but a recording layer and a reflective layer are formed on a thin substrate similar to the present embodiment. In this case, for example, the present invention can be applied to the manufacture of an optical information recording medium in which the recording layer has a multilayer structure.

It is a schematic diagram which shows a part of cross section of the optical information recording medium of this invention. It is a schematic cross section which shows the process of forming a 2nd board | substrate. It is a schematic cross section which shows the process of forming a 2nd board | substrate. It is a schematic cross section which shows the process of forming a 2nd board | substrate. It is a schematic cross section which shows the process of forming a 2nd board | substrate. It is a schematic cross section which shows the process of forming the optical information recording medium of this invention. It is a schematic cross section which shows the process of forming the optical information recording medium of this invention. It is a schematic cross section which shows the process of forming the optical information recording medium of this invention. It is a schematic cross section which shows the process of forming the optical information recording medium of this invention. It is a schematic cross section which shows the process of forming the optical information recording medium of this invention. It is a schematic diagram which shows a part of cross section of the conventional optical information recording medium.

Explanation of symbols

1, 1 'optical information recording medium 2, 2' first substrate
3, 3 'second substrate
4, 4 'recording layer 5, 5' reflective layer
6, 6 'Adhesive layer 7 Protective layer 10 Press member 11 Fixing member 12 Cutter 31 Intermediate substrate 32 Precursor substrate 33 Ring-shaped frame

Claims (2)

A circular first substrate having a through-hole in the center, and a light transmissive second substrate that is substantially the same shape as the first substrate and is thinner than the first substrate. The second substrate has a spiral or concentric guide groove on one surface, and a recording layer and a reflective layer are sequentially formed in the region where the guide groove is formed on the second substrate. In the method of manufacturing an optical information recording medium formed by bonding the surface of the substrate on which the recording layer and the reflective layer are formed and one surface of the first substrate facing each other with an adhesive layer,
Forming the first substrate by injection molding;
A guide groove is formed on one surface by injection molding and an intermediate substrate thicker than the thickness of the second substrate is formed, and a surface opposite to the surface on which the guide groove is formed on the intermediate substrate is Pressing with a pressing member having a circular pressing portion equal to or larger than the diameter of the second substrate to form a precursor substrate in which the second substrate and the ring-shaped frame are integrated; and
Forming a recording layer in a region of the precursor substrate where the guide groove is formed, and then forming a reflective layer;
Bonding one surface of the first substrate and the surface of the second substrate on which the recording layer and the reflective layer are formed;
Cutting the second substrate from the precursor substrate to have the same shape as the first substrate;
A method for producing an optical information recording medium, comprising: A circular first substrate having a through-hole in the center, and a light transmissive second substrate that is substantially the same shape as the first substrate and is thinner than the first substrate. The second substrate has a spiral or concentric guide groove on one surface, and a recording layer and a reflective layer are sequentially formed in the region where the guide groove is formed on the second substrate. In the optical information recording medium formed by bonding the surface on which the recording layer and the reflective layer of the substrate are formed and one surface of the first substrate facing each other with an adhesive layer,
The second substrate is
A guide groove is formed on one surface by injection molding and an intermediate substrate thicker than the thickness of the second substrate is formed,
The intermediate substrate is cut from a precursor substrate formed by pressing the surface opposite to the surface on which the guide groove is formed with a pressing member having a circular pressing portion having a diameter equal to or larger than the diameter of the second substrate. An optical information recording medium comprising:

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