JPH1186344A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical recording medium which hardly deforms by successively depositing a memory layer containing an org. dye, metal reflection layer and protective layer on a first substrate to prepare a first disk, successively depositing a metal reflection layer and protective layer on a second substrate to prepare a second disk, and laminating the first disk and the second disk with the protective layers facing each other with an adhesive comprising a cationic polymn. hardening resin of delayed action. SOLUTION: A first disk 10 of the optical disk consists of a light-transmitting substrate 1a having a region including grooves 2a, a recording layer 3 formed on this region, and further a reflection layer 4a and a protective layer 5a formed to cover the recording layer 3. In the recording layer 3, information is carried by forming fine recesses or projections as pits which represent the information. The second disk 20 consists of a light-transmitting substrate 1b having a region including grooves 2b, a reflection layer 4b and a protective layer 5b formed in this region. These substrates are laminated with the protective layers 5a, 5b facing each other with an adhesive layer 6 comprising a slow-curing cationic polymn. hardening resin. Thus, the obtd. medium hardly deforms under any environmental conditions and has higher reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical recording medium.

[0002]

2. Description of the Related Art Conventionally, as an optical disk such as a video disk, as shown in FIG. 2, a pit row or a groove for carrying information is formed concentrically or spirally on one surface of a light-transmitting substrate 31, and the upper side thereof is formed. A double-sided recording disk is known in which a pair of disks in which a reflective layer 34 and a protective layer 35 are sequentially formed are bonded together with an adhesive layer 36 with the protective layer 35 facing each other, and a center provided at the center of the disk is known. Aim at the hole, clamp and rotate the disc,
Irradiate the read beam to the recording area on each side of the disc,
The information is optically reproduced.

For example, a write-once type CD-R disk or DVD-R disk is an optical recording medium provided with a dye film and capable of writing information only once, and has a preformed groove.

[0004] In such a laminated optical disc, a hot-melt adhesive is generally used as an adhesive layer.

[0005]

However, since the hot melt type adhesive is thermoplastic, it is inferior in heat resistance.
There is a problem that the disk is easily deformed or peeled off by heat. Therefore, it is conceivable to use a UV-curable resin having good heat resistance as an adhesive for laminating disks. However, since ultraviolet rays are irradiated through a substrate, a reflective layer, and a protective layer, most of the ultraviolet rays are reflected, It will be absorbed and not enough UV light will reach the UV curable resin,
It takes time to cure. In addition, as a UV-curable adhesive mainly containing a radical-polymerizable material, the curing is hindered by oxygen. Become.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide an optical recording medium which is not easily deformed.

[0007]

An optical recording medium according to claim 1, comprising: a first disk on which a recording layer containing an organic dye, a metal reflective layer, and a protective layer are sequentially laminated on a first substrate; A second disk in which a metal reflective layer and a protective layer are sequentially laminated on a second substrate is bonded to each other with an adhesive layer made of a slow-acting cationically polymerizable resin, with the protective layers facing each other.

[0008] The invention described in claim 2 is the first invention.
The optical recording medium according to claim 1, wherein the first and second substrates are made of a synthetic resin substrate having a thickness of 0.6 ± 0.03 mm, and emit a laser beam having a wavelength of 600 to 700 nm and a numerical aperture of 0.55 to
It is characterized in that recording and reproduction are performed by condensing light on the recording layer through the substrate using an objective lens of 0.70.

[0009] The invention described in claim 3 is the first invention.
The optical recording medium according to claim 1, wherein an identification symbol directly engraved with a laser beam is provided on a bonding surface side of the substrate in a range including a clamp region of at least one of the first and second substrates. And

[0010]

The optical recording medium according to the present invention is made of a slow-acting cationically polymerizable resin by making the first disk and the second disk similar in structure and manufactured in the same process, with the protective layer facing each other. By bonding with an adhesive layer made of such a material, it is difficult to be deformed under environmental conditions, and the reliability is improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an optical disk of the present invention. As shown in FIG. 1, this optical disc has a groove on a light-transmitting substrate 1a having a groove 2a formed on a main surface thereof except for an outer peripheral portion (outer peripheral, non-recording area) and an inner peripheral portion (inner peripheral non-recording area). A recording layer 3 carrying information is formed by forming pits representing information by fine irregularities on a region including 2a, and a reflective layer 4a is formed to cover the recording layer 3;
The first disk 10 on which the protective layer 5a is formed so as to cover the reflective layer 4a, and the reflective layer 4b is formed on a region including the groove 2b of the translucent substrate 1b on which the groove 2b is formed. And a second disk 20 on which a protective layer 5b is formed so as to cover the first disk 10 and the second disk 20.
It is configured by bonding the surfaces having a and 5b so as to face each other.

The material for forming the light-transmitting substrate may be any material having a light-transmitting property with respect to recording or reproducing light, and examples thereof include synthetic resins such as polycarbonate (PC) and polymethyl methacrylate (PMMA), and glass. Is raised. Among them, polycarbonate is preferably used because of its excellent heat resistance and dimensional stability. These translucent substrates 1a and 1b are formed by injection molding when the forming material is a synthetic resin. The size and shape of the light-transmitting substrate may be appropriately determined according to the use of the optical disc. For example, a circular shape having a diameter of about 120 mm and a thickness of 0.2 to 1.2 mm, for example, about 0.6 mm A substrate is preferably used.

The grooves 2a and 2b are formed on the light-transmitting substrate 1 in advance.
a, 1b, and the recording layer 3 is a transparent substrate 1
Only a is formed with organic dyes such as cyanine, merocyanine, phthalocyanine, and azo dye.

The reflection layers 4a and 4b are made of a metal film having a thickness of 300 to 1000 angstroms made of aluminum or aluminum alloy or the like, and are formed by a sputtering method, a vacuum evaporation method or the like.

The protective layers 5a and 5b are made of a radical polymerization type ultraviolet curable resin and have a thickness of 5 to 20 μm.
It is formed by a spin coating method, a roll coater method, a screen printing method, or the like.

The adhesive layer 6 is made of an ultraviolet-curable adhesive mainly composed of a cationic polymerization resin, and has a thickness of 20.
４０40 μm.

Next, a method of manufacturing the optical disk of the present invention will be described. First, a pair of light-transmitting substrates having a recording area in which a groove is formed on the main surface excluding an outer peripheral portion and an inner peripheral portion is prepared. This translucent substrate is obtained by injection molding a synthetic resin such as a polycarbonate resin using a stamper. Its size is 120m in diameter
m and a thickness of 0.6 ± 0.03 mm.

On one translucent substrate, an azo dye or the like obtained by dissolving a recording layer in a recording area including a groove with a solvent, for example, is uniformly applied to the surface of the translucent substrate 1a by means such as spin coating. This is formed by coating.

Next, the outer periphery and the inner periphery of the light-transmitting substrate are covered with a mask, and aluminum or an aluminum alloy is deposited or sputtered to a thickness of 300 to 1000 on the recording area excluding the outer periphery and the inner periphery. An Angstrom metallic reflective layer is formed. At this time, the recording layer is not formed on one of the translucent substrates, and the metallic reflection layer is formed directly on the recording area.

Next, an ultraviolet curable resin of a radical polymerization type is coated so as to cover the outer peripheral portion, the inner peripheral portion, and the reflective layer of the translucent substrate.
The protective layer is formed by a spin coating method, a screen printing method, a roll coater method, or the like to a thickness of 5 to 20 μm and irradiating ultraviolet rays. Here, as the radical polymerization type ultraviolet curable resin, for example, an ultraviolet curable resin “SD-211” manufactured by Dainippon Ink and Chemicals, Inc. is used. Such an ultraviolet curable resin is a colorless transparent liquid having a viscosity of 28 cps at 25 ° C.

Next, an ultraviolet-curable adhesive mainly composed of a cationic polymerization resin is applied to a thickness of 10 to 20 μm by spin coating, screen printing, roll coater or the like to form an adhesive layer. And irradiate it with ultraviolet light. As such an adhesive, an adhesive having a long-lasting effect, that is, an adhesive which takes a long time to cure after ultraviolet irradiation is preferable. For example, an ultraviolet-curable adhesive “95A01X” manufactured by Sony Chemical Corporation is used. Such an adhesive contains a cationic polymerization type epoxy resin as a main component, is a white opaque paste, and has a 50,000-100,000 c.
It has a viscosity of ps (BH type viscometer, 2 rpm measuring device). When this adhesive is used, the adhesive is applied by screen printing and irradiated with ultraviolet rays of 100 to 500 mJ / cm2.

Next, after a pair of light-transmitting substrates are overlapped with the adhesive layer interposed therebetween, 50 to 500 gf / c
Pressure is applied at a pressure of m2 to cure the adhesive. At this time, the adhesive takes a long time to cure, so that the adhesive can be applied between the substrates in an overlapped state, and no excessive stress is applied.

The above-mentioned diameter of 120 mm and thickness of 0.6 ±
In an optical recording medium manufactured using a 0.03 mm translucent substrate, laser light having a wavelength of 600 to 700 nm is applied to the recording layer through the translucent substrate using an objective lens having a numerical aperture of 0.55 to 0.70. In the case of performing recording and reproduction by condensing light, effective recording and reproduction performance can be obtained.

Further, the first and second optical recording media described above
By providing an identification symbol (7 shown in FIG. 1) directly engraved with a laser beam on the bonding surface side of the substrate in a range including the clamp region of at least one of the substrates, another optical reading not shown or shown The device makes it possible to identify the optical recording medium.

In the above embodiment, the adhesive layer is
It may be formed on only one of the pair of disks, or may be formed on both. Further, in the above-described embodiment, the read-only type bonded optical disk has been described. However, it is needless to say that the present invention can be applied to a writable type disk in which a recording layer is formed between a recording area of a substrate and a reflective layer. . Furthermore, the present invention can also be applied to a single-sided recording bonded disk in which one of the pair of disks is a dummy disk.

[0026]

As described above, according to the present invention, the structures of the first disk and the second disk are approximated,
And by the same process, the protective layer is opposed to each other and bonded by an adhesive layer made of a slow-acting cationically polymerized resin. Since the obtained adhesive has fluidity, it is possible to provide an optical recording medium that is not easily deformed under environmental conditions, and it is possible to improve the reliability of the optical disk.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view showing a configuration of an optical disc in the present invention.

FIG. 2 is a schematic side sectional view showing a configuration of a conventional optical disk.

[Description of Signs] 1a, 1b, 31 ··· Translucent substrate 2a, 2b ··· Groove 3 ··· Recording layer 4a, 4b, 34 ··· Reflective layer 5a, 5b, 35 ··· ... protective layer 6, 36 ... adhesive layer 7 ... identification code 10 ... first disk 20 ... second disk

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigenori Murakami 2680 Nishihanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Prefecture Inside Pioneer Video Co., Ltd. (72) Inventor Jun Kondo 2680 Nishihanawa, Tatomicho, Nakakoma-gun, Yamanashi Pioneer Video Inside (72) Inventor Ayumi Mimori 2680, Nishi-Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Prefecture Inside (72) Inventor Taki Kusama, 2680 Nishi-Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Pioneer Video Corporation ( 72) Inventor Makoto Matsukawa 2680 Nishihanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Prefecture Inside Pioneer Video Corporation

Claims (3)

[Claims] 1. A first disk in which a recording layer containing an organic dye, a metal reflective layer, and a protective layer are sequentially laminated on a first substrate, and a metal reflective layer and a protective layer are sequentially laminated on a second substrate. An optical recording medium characterized in that the second disk is bonded to the second disk with an adhesive layer made of a slow-acting cationically polymerizable resin with the protective layer facing the second disk. 2. The method according to claim 1, wherein the first and second substrates have a thickness of 0.6.
It consists of a synthetic resin substrate of ± 0.03 mm and has a wavelength of 600
2. The optical recording medium according to claim 1, wherein a laser beam having a wavelength of 700 nm is focused on the recording layer through the substrate by using an objective lens having a numerical aperture of 0.55 to 0.70 to perform recording and reproduction. 3. An identification mark directly engraved with a laser beam on a bonding surface side of a substrate in a range including a clamp region of at least one of the first and second substrates. Item 2. The optical recording medium according to Item 1.