JP2003030896A - Optical information recording medium - Google Patents

Abstract

[PROBLEMS] To provide an optical information recording medium containing a dye in a recording layer, capable of recording and reproducing by irradiating a laser from the light transmitting layer side, and capable of increasing the capacity. An optical information recording medium having at least a light reflection layer, a recording layer, and a light transmission layer on a substrate in order,
The recording layer contains a dye, the dissolution rate of the dye in the light transmitting layer is 0.1% by mass or less of the light transmitting layer, and a laser is incident from the light transmitting layer side to record information. The optical information recording medium is characterized by being reproduced.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium having a large capacity and containing a dye in a recording layer. 2. Description of the Related Art As shown in FIG. 2, an optical information recording medium such as a conventional CD-R has a recording layer 1 on a substrate 10.
1, a reflective layer 12 and a protective layer 13 are laminated in this order, and a laser is incident from the substrate 10 side to record / reproduce information. Substrate 1 to transmit laser
0 is composed of a light-transmitting layer that transmits light. In order to increase the recording density in the optical information recording medium having such a configuration, it is effective to reduce the laser spot diameter. Laser spot diameter is λ / NA
Since it is proportional to (λ: laser wavelength, NA: lens aperture ratio), in order to reduce the laser spot diameter, it is necessary to decrease λ or increase NA.
When increasing the NA, the spherical aberration increases in proportion to the fourth power of the NA, so it is advantageous to reduce the thickness of the light transmission layer. For example, a DVD-R having a recording capacity 7 times or more that of a CD-R has a larger NA (CD-R) than the CD-R.
R: 0.45, DVD-R: 0.6) and short wavelength laser (CD-R: 780 nm, DVD-R: 635 nm or 650 nm) are used. The spherical aberration is reduced by setting the thickness of a certain substrate to 0.6 mm which is half of the CD-R.
Two discs are bonded together. However, considering further increase in capacity, it is required to further reduce the thickness of the substrate, but there is a limit to reducing the thickness of the substrate. Therefore, as a new means for increasing the capacity, there has been proposed an optical information recording medium for recording and reproducing information by entering a laser from the protective layer side, not from the substrate side. Japanese Patent Application Laid-Open No. 11-273147 discloses an optical information recording medium provided with a light transmission layer comprising a pressure-sensitive adhesive sheet and a transparent film, and recording and reproducing information by irradiating a laser from the light transmission layer side. Has been. JP 2
In Japanese Patent No. 000-30299, the thickness d of the protective layer and the aperture ratio NA of the lens are (NA) ⁴ × d ≦ 0.0744,
An optical information recording medium having a protective layer formed so as to satisfy the above relationship is disclosed. However, these optical information recording media may damage the recording layer in the process of forming the protective layer. Japanese Patent Application Laid-Open No. 2000-30299 does not describe a recording layer when a protective layer is provided. In view of the above, the present invention provides the following:
An object of the present invention is to provide an optical information recording medium containing a dye in a recording layer, capable of recording / reproducing by irradiating a laser from the light transmitting layer side, and capable of increasing the capacity. The above object can be achieved by the present invention described below. That is, the present invention is an optical information recording medium having at least a light reflection layer, a recording layer, and a light transmission layer on a substrate in order, wherein the recording layer contains a dye, and the dye is transferred to the light transmission layer. The dissolution rate of
An optical information recording medium characterized in that the content is 0.1% by mass or less of the light transmission layer, and information is recorded / reproduced by entering a laser from the light transmission layer side. In a particularly preferred embodiment of the present invention, the light transmission layer is made of an ultraviolet curable resin. The substrate has a thickness of 1.0 to 1.2 mm, and the light transmission layer has a thickness of 1 to 200 μm. A particularly preferable method for producing the optical information recording medium according to the present invention includes at least a light transmitting layer forming step of forming a light transmitting layer on the recording layer by a spin coating method. BEST MODE FOR CARRYING OUT THE INVENTION << Optical Information Recording Medium >> As shown in FIG. 1, an optical information recording medium of the present invention comprises at least a reflective layer 2, a recording layer 3, and an optical material on a substrate 1. The transparent layer 4 is sequentially provided, and other layers such as an undercoat layer are provided as necessary.
Hereinafter, the optical information recording medium will be described in detail while explaining each layer. <Substrate 1> As the substrate 1, various materials used as substrate materials for conventional optical information recording media can be arbitrarily selected and used. Specifically, glass; acrylic resin such as polycarbonate and polymethyl methacrylate; vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer; epoxy resin; amorphous polyolefin; polyester; metal such as aluminum;
Etc., and these may be used in combination as desired. Among the above materials, amorphous polyolefin and polycarbonate are preferable, and polycarbonate is particularly preferable from the viewpoints of moisture resistance, dimensional stability, and low price. Moreover, it is preferable that the thickness of the board | substrate 1 shall be 1.0-1.2 mm, and it is more preferable to set it as 1.05-1.15 mm. The substrate 1 has projections and depressions (pregrooves) representing information such as tracking guide grooves or address signals.
Is formed. The pregroove track pitch is
It is preferable to be in the range of 100 to 800 nm,
More preferably, it is set to -700 nm. Further, the depth of the pregroove (groove depth) is preferably in the range of 10 to 200 nm, and more preferably in the range of 30 to 180 nm. An undercoat layer is preferably formed on the surface of the substrate 1 on the side where the light reflecting layer 2 described later is provided for the purpose of improving flatness and adhesion. Examples of the material for the undercoat layer include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleic anhydride copolymer, polyvinyl alcohol, N-methylol acrylamide, styrene / vinyl toluene copolymer,
Chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester,
Polymer materials such as polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, polyethylene, polypropylene, and polycarbonate; surface modifiers such as silane coupling agents; The thickness of the undercoat layer is generally in the range of 0.005 to 20 μm,
Preferably it is the range of 0.01-10 micrometers. <Light Reflecting Layer 2> The light reflecting layer 2 is made of a light reflecting material having a high reflectivity with respect to the laser beam. The reflectance is preferably 70% or more. As a light reflective material having a high reflectance, Mg, Se, Y, Ti, Z
r, Hf, V, Nb, Ta, Cr, Mo, W, Mn, R
e, Fe, Co, Ni, Ru, Rh, Pd, Ir, P
t, Cu, Ag, Au, Zn, Cd, Al, Ga, I
Mention may be made of metals such as n, Si, Ge, Te, Pb, Po, Sn, Bi, and semimetals or stainless steel. These light reflective materials may be used alone,
Alternatively, a combination of two or more kinds or an alloy may be used. Among these, preferred are Cr, Ni,
Pt, Cu, Ag, Au, Al and stainless steel. Particularly preferred is Au, Ag, Al or an alloy thereof, and most preferred is Au, Ag or an alloy thereof. The thickness of the light reflecting layer 2 is generally 1
The range is 0 to 300 nm, and the range is preferably 50 to 200 nm. <Recording layer 3> The recording layer 3 contains a dye as a recording material. Examples of the dye contained in the recording layer 3 include a cyanine dye, an oxonol dye, a metal complex dye, an azo dye, and a phthalocyanine dye.
Of these, phthalocyanine dyes are preferable. JP-A-4-74690, JP-A-8-127174, 11-53758, 11-334204, 11-33420.
No. 5, No. 11-334206, No. 11-33
No. 4207, JP-A 2000-43423, 2000-108513, and 2000-1.
The dyes described in Japanese Patent No. 58818 are also preferably used. The thickness of the recording layer 3 is generally in the range of 20 to 500 nm, preferably in the range of 30 to 300 nm, and more preferably in the range of 50 to 100 nm. The recording layer 3 can contain various anti-fading agents in order to improve the light resistance of the recording layer. As the antifading agent, a singlet oxygen quencher is generally used. As a singlet oxygen quencher,
Those already described in publications such as known patent specifications can be used. Specific examples thereof include Japanese Patent Laid-Open No. 58-1.
75693, 59-81194, 60
No. 18387, No. 60-19586, No. 6
No. 0-19587, No. 60-35054, No. 60-36190, No. 60-36191,
60-44554, 60-45555, 60-44389, 60-44390, 60-54892, 60-47069
Gazettes, 63-209995 gazettes, Japanese Patent Laid-Open No. 4-25
No. 492, JP-B-1-38680, JP-A-6-26028, etc., German Patent 3503
No. 99 specification, and the Journal of the Chemical Society of Japan, October 1992, page 1141, etc. can be mentioned. The amount of the antifading agent such as the singlet oxygen quencher used is usually in the range of 0.1 to 50% by weight, preferably 0.5 to 45% by weight, based on the amount of the dye. The range is more preferably 3 to 40% by mass, particularly preferably 5 to 25% by mass. <Light Transmission Layer 4> The light transmission layer 4 serves as a protective layer and prevents moisture from entering and scratches. The material constituting the light transmission layer 4 is preferably an ultraviolet curable resin, a visible light curable resin, a thermosetting resin, silicon dioxide, or the like, and more preferably an ultraviolet curable resin. Examples of the ultraviolet curable resin include an ultraviolet curable resin such as “SD-640” manufactured by Dainippon Ink. Also, SD-347 (Dainippon Ink Co., Ltd.), SD-694 (Dainippon Ink Co., Ltd.), SK
CD1051 (manufactured by SKC) or the like can be used. The thickness of the light transmission layer 4 is preferably in the range of 1 to 200 μm, and more preferably in the range of 50 to 150 μm. Also,
Since the light transmission layer 4 is used as a laser optical path as described later, it is necessary to have transparency. Here, “transparency” means that the recording light and the reproduction light are so transparent that the light is transmitted (transmittance: 90 or more). Here, the dissolution rate of the dye contained in the recording layer into the light transmission layer 4 is 0.1% by mass of the light transmission layer.
It is necessary to make it below, and the range of 0.00001-0.01 mass% is more preferable. The dissolution rate is 0.1% by mass
Exceeding this causes unevenness in the dye layer, resulting in poor recording and reproduction because clean pits cannot be formed. Therefore, it is necessary to appropriately select and use the dye and the material constituting the light transmission layer 4 so that the dissolution rate does not exceed 0.1% by mass. For example, the dissolution rate when an ultraviolet curable resin is used is preferably measured as described below. That is, the dye constituting the recording layer is gradually added to the ultraviolet curable resin before curing, the transmittance of the supernatant liquid when saturated is measured with an absorptiometer, and the solubility is measured from the transmittance. << Method for Producing Optical Information Recording Medium >> The method for producing an optical information recording medium of the present invention comprises at least (1) a light reflecting layer forming step, (2) a recording layer forming step, and (3) a light transmitting method. In this light transmission layer formation step, the light transmission layer is formed on the recording layer by a spin coating method. Hereinafter, each processing step will be described. (1. Light reflecting layer forming step) The light reflecting layer forming step is a step of forming a light reflecting layer on a substrate on which a predetermined pregroove or the like is formed. The light reflecting layer can be formed on the substrate, for example, by vapor deposition, sputtering or ion plating of the light reflecting material. In forming the light reflection layer, a mask is usually used, and the formation region of the light reflection layer can be adjusted thereby. When forming the undercoat layer before forming the light reflecting layer, after preparing a coating solution by dissolving or dispersing the above-described undercoat layer material in an appropriate solvent, spin coating this coating solution, An undercoat layer can be formed by applying to the substrate surface (the surface on which the pregroove or the like is formed) by a coating method such as dip coating or extrusion coating. (2. Recording layer forming step) After the light reflecting layer is formed, the recording layer is formed on the light reflecting layer through the recording layer forming step. The recording layer is prepared by dissolving a recording material such as a dye in a suitable solvent together with a binder or the like to prepare a coating solution, and then coating the coating solution on the light reflecting layer formed on the substrate surface. After forming, it is formed by drying. The concentration of the recording substance in the coating solution is generally 0.01 to 1
The range is 5% by mass, preferably 0.1 to 10% by mass.
More preferably, it is the range of 0.5-5 mass%, Most preferably, it is the range of 0.5-3 mass%. Examples of the solvent for the coating solution include esters such as butyl acetate, ethyl lactate and 2-methoxyethyl acetate;
Ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; hydrocarbons such as methylcyclohexane; ethers such as tetrahydrofuran, ethyl ether and dioxane; Ethanol, n-propanol,
Alcohols such as isopropanol and n-butanol diacetone alcohol; fluorine-based solvents such as 2,2,3,3-tetrafluoropropanol; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and propylene glycol monomethyl ether; Etc. The above solvents can be used alone or in combination of two or more in consideration of the solubility of the recording material used. Various additives such as an antioxidant, a UV absorber, a plasticizer, and a lubricant may be further added to the coating solution depending on the purpose. When a binder is used, examples of the binder include gelatin, cellulose derivatives, dextran,
Natural organic polymer materials such as rosin and rubber; polyethylene,
Hydrocarbon resins such as polypropylene, polystyrene and polyisobutylene, vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl chloride / polyvinyl acetate copolymers, acrylic resins such as polymethyl acrylate and polymethyl methacrylate Synthetic organic polymers such as polyvinyl alcohol, chlorinated polyethylene, epoxy resins, butyral resins, rubber derivatives, and initial condensates of thermosetting resins such as phenol / formaldehyde resins. When using a binder as a material for the recording layer,
The amount of the binder used is generally in the range of 0.01 to 50 times (mass ratio) with respect to the recording substance, preferably 0.
It exists in the range of 1 time amount-5 times amount (mass ratio). The concentration of the recording material in the coating solution thus prepared is generally 0.
It is in the range of 01-10% by mass, preferably 0.1-5
It is in the range of mass%. Examples of the coating method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method. The recording layer may be a single layer or a multilayer. (3. Light Transmission Layer Formation Step) After the recording layer is formed, a light transmission layer is formed on the recording layer through a light transmission layer formation step. The light transmission layer is formed by a spin coating method. By applying the spin coating method, the light transmission layer can be formed without damaging the recording layer (dissolution of the dye, chemical reaction between the dye and the light transmission layer material, etc.). The number of rotations during spin coating is 50 to 8 from the viewpoint of uniform layer formation and prevention of damage to the recording layer.
000 rpm, preferably 100 to 5000
More preferably, rpm. When an ultraviolet curable resin is used for the light transmissive layer, after the light transmissive layer is formed by spin coating, the ultraviolet light is irradiated from above the light transmissive layer by an ultraviolet irradiation lamp (metal halide lamp), and the ultraviolet curable resin is irradiated. Is cured. Further, in order to eliminate unevenness in the thickness of the light transmitting layer to be formed, a treatment such as leaving it for a certain period of time before curing the resin may be appropriately performed. The optical information recording medium of the present invention is manufactured through the above steps. In addition, you may provide a well-known process suitably before and after each process. << Information Recording Method and Reproducing Method Using Optical Information Recording Medium of Present Invention >> Next, a method for recording information on an optical information recording medium and a method for reproducing recorded information according to the present invention will be described. . For example, information is recorded on the optical information recording medium as follows. First, the optical information recording medium is moved at a constant linear velocity (1.2 to 1.4 m /
Seconds, 3.49-3.9m / for DVD format
Seconds) or while rotating at a constant angular velocity, the recording laser is irradiated from the light transmission layer side. By laser irradiation
The recording layer absorbs the light and the temperature rises locally, causing a physical or chemical change (for example, generation of pits) to change its optical characteristics, thereby recording information. On the other hand, the recorded information is reproduced by detecting the reflected light by irradiating the laser from the light transmission layer side while rotating the optical information recording medium at the same constant linear velocity as described above. it can. The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Example 1) -Manufacture of optical information recording medium- A spiral groove (depth: 156 nm, width: 1.1 mm, diameter: 120 mm) by an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd.) 290 nm, track pitch 0.
A polycarbonate resin substrate having a thickness of 74 μm was prepared. Silver was sputtered on the surface of the manufactured substrate having a groove to form a 150 nm-thick light reflecting layer (light reflecting layer forming step). Next, 1.5 g of a dye represented by the following chemical formula (1) was dissolved in 100 ml of 2,2,3,3-tetrafluoropropanol to prepare a dye coating solution. This dye coating wave is applied to the spin coating method (rotation number: 300
(3000 rpm, 23 ° C., 50% RH) to form a recording layer containing a dye by coating on the light reflecting layer (recording layer forming step). ## STR1 ## An ultraviolet curable resin SD-3 is formed on the recording layer.
47 (Dai-Cure Clear SD-, manufactured by Dainippon Ink & Chemicals, Inc.
347) by spin coating method (rotational speed: 80-2000r)
pm) and irradiating ultraviolet rays with a metal halide lamp to form a light transmissive layer having a thickness of 10 μm (light transmissive layer forming step) to produce an optical information recording medium. On the other hand, the UV curable resin SD of the dye.
The dissolution rate with respect to -347 was determined as follows. That is, 1 kg of the uncured UV curable resin S
100 mg of the dye was added to D-347, stirred with a stirrer for 10 minutes, and the transmittance of the supernatant was measured with an absorptiometer to determine the dissolution rate. The dissolution rate was less than 0.1% by mass. (Comparative Example 1) In the light transmitting layer forming step,
SD-17 instead of the UV curable resin SD-347
An optical information recording medium was manufactured in the same manner as in Example 1 except that 00 (dissolution rate of the dye: 0.2% by mass) was used. -Evaluation of optical information recording medium- With respect to the optical information recording medium obtained in Example 1 and Comparative Example 1, N / A was 0.6 using a DDU-1000 (manufactured by Pulstec). The 8-16 modulation signal was recorded at a laser wavelength of 650 nm and a constant linear velocity of 3.49 m / s. In Example 1, the recording amplitude was observed, but in Comparative Example 1, the recording amplitude was not observed. This is presumably because, in Comparative Example 1, the recording layer was damaged because the solubility of the dye in the ultraviolet curable resin was high in the light transmission layer forming step. According to the present invention, an optical information recording is possible which contains a dye in the recording layer, can be recorded and reproduced by irradiating a laser from the light transmitting layer side, and can have a large capacity. A medium can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing an example of a layer structure of an optical information recording medium of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a layer structure of a conventional optical information recording medium. DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Light reflection layer 3 ... Recording layer 4 ... Light transmission layer

Claims (1)

1. An optical information recording medium comprising, on a substrate, at least a light reflecting layer, a recording layer, and a light transmitting layer in order,
The recording layer contains a dye, the dissolution rate of the dye in the light transmission layer is 0.1% by mass or less of the light transmission layer, and a laser is incident from the light transmission layer side to record information. An optical information recording medium that is reproduced.