KR100257890B1 - Organic optical recording medium - Google Patents

Abstract

PURPOSE: An organic optical recording medium is provided to add a specific pigment to a recording layer, to perform recording and regenerating by a short wavelength light source, and to be used as every kind of high-density and high-capacity information recording medium and video recording medium. CONSTITUTION: A substrate(1) where a pre-groove is formed, a recording layer(2), a reflective layer(3) and a protective layer(4) are disposed. In a recording operation, if laser is collected to the recording layer(2), a pigment of the recording layer(2) absorbs the laser and generates heat. The generated heat melts a part of the substrate(1), and a denatured pigment is mixed, thereby forming recording on the recording layer(2) near the pre-groove of the substrate(1) in a bump type. When regenerating the recording, recording laser is used and an output is lower than that of the recording operation. Information is read by the difference between reflectivity in a recorded part and a non-recorded part when irradiating laser on a surface of a disk.

Description

Organic optical recording media

1A is a cross-sectional view of an organic optical recording medium according to the present invention.

1 (b) is a cross-sectional view showing a recording state of an organic optical recording medium according to the present invention.

2 is a structural diagram of a shortwave light source used in the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic optical recording medium. In particular, a specific color is added to a recording layer to record and reproduce by a short wavelength light source. A recording medium.

The explosive increase of various kinds of information due to the high degree of informatization of society in general necessitates high density, large capacity and high speed of storage media. Recently, the most practical storage method is that the information is recorded in the magnetic way according to the magnetization direction of the magnetic medium magnetic material. Examples of the use thereof include video tapes, audio tapes, and profi discs.

However, as the amount of information increases due to social development, a large amount of recording media is required, and thus a magneto-optical recording media has emerged. In the magneto-optical method, unlike the magnetic material used for the magnetic recording medium, the magnetization direction is perpendicular to the surface of the recording film, and the coercivity to maintain the magnetization direction is 5 to 10 times higher than that of the magnetic medium. Difficult to do Therefore, in order to change the magnetic direction, it is possible to record the information according to the magnetic direction by changing the magnetic direction to an external magnetic field in a state in which light is connected to 1 탆 or less using a laser and heated above the Curie temperature. When recording in this manner, the information recording unit can be made smaller than 1 [mu] m and can have a recording density of 10 to 1000 times that of the magnetic memory method, and the record storage is easy and the life is long by using the non-contact memory reproducing method.

However, such a magneto-optical (MOD) method uses a heavy metal-based magnetic material and requires a vacuum deposition or sputtering device in the manufacturing process, which causes a lot of difficulties in manufacturing. In order to solve this disadvantage, a method of using an organic optical recording material has been proposed.

The method of using such an organic optical recording material can be divided into a write once read many (WORM) type that can only be read after write once and an eraseable type that can be erased after write, depending on whether it can be erased. WORM type, as mentioned in Japanese Unexamined Patent Publication Nos. 57-46362, 58-197088, 59-5096, 63-179792 and the like, is coated with a polymer resin and coated with a pigment that can absorb a laser on the reflective layer. It is made by coating a protective layer on top. In the case of recording using this, when the laser is focused on the recording layer within 1 µm, heat is generated by the dye absorbing the laser, and this heat decomposes the polymer resin to form a pit, thereby enabling recording. During recording and playback, information (logic 1 or 0) is read due to the difference in reflectance between the part with and without the pit. In the WORM type, since the recorded portion becomes the decomposition form of the polymer, it is impossible to record again after erasing the recording.

Rewritable type is a method of forming and erasing bumps or pits, and using liquid crystals or using phase shifts (JP-A-58-199345, 63-74135, 3-3-241241, 3). -256242, 3-266235, etc.), but the bump method is widely applied. The method of using bumps is to disperse the pigment in the organic polymer so that the polymer is thermally expanded when recorded by the laser to make bumps and maintain the shape so that the recording is possible. Such a description of an erasable optical recording material using organic dyes is described in US Patent 183719, US4719615 US 835960, US 944423 to Optical Data Inc. (ODI). The substrate uses a transparent resin such as polycarbonate or polymethyl methacrylate.

When the record is read using such an erasable optical recording material, the record is read by the difference in reflectance between the unrecorded portion and the portion recorded in the bump form by irradiating the recording medium with the weak output of the recording laser. Attempts have been made to improve the reflectance by the dye itself (Japanese Patent Laid-Open Nos. 58-112790, 62-146682, H1-206093), but the reflectance by the dye is limited.

At the time of erasing, when the erasing laser is focused on the erasing layer and the erasing layer is heated above the Tg (glass transition temperature), the resistance to the restoring force of the recording layer is weakened, and the original layer is restored by the restoring force of the recording layer. The bumps pushed up to show rain have to be considered for reliability when repeated use, so an improvement therefor (Japanese Patent Laid-Open No. 63-207691) is required, but the application to actual optical recording media is skeptical.

Currently, the optical recording medium of WORM type has been made practically in the form of a disc, and has been developed in the field of data storage disc, recordable audio CD, photo CD, etc., and Fuji (Japanese Patent 2-67183, 4-76836, 4- 102242), TDK (Japanese Patent 2-24437, 2-273339, 2-312020, 3-66042, 3-203694, 3-224792, 4-25492, 4-25493, 4-28588), Pioneer (Japanese Patent 3- 203690, 3-203691, 3-203692, 3-203693) Daio Yuden (Japanese Patent 2-132649, 2-132654, 2-132656, 2-132657, 2-206093, 2-84384), Sony (Japanese Patent 3- 46135, 4-70380) and many other patents.

Recently, many efforts have been made to shorten the light source used for recording optical discs. When the wavelength of the light source is reduced, the recording capacity on the same optical recording medium is further increased. The present invention was developed based on the fact that recording of a moving image of several hours can be made even with a disc of a size. The present invention is characterized by maximizing the recording capacity per unit area by using a short wavelength of the laser light source used for recording such a WORM-type disk or tape-type recording medium, and by using an organic dye corresponding thereto. .

That is, the present invention is an optical recording medium having a recording layer containing a cyanine dye represented by the following general formula (I) or (II) on a substrate.

(In the formula (I) or (II), Z is an atomic group forming a benzene ring or a naphthalene ring, R ₁ , R ₂ is one of alkyl, alkoxy, hydroxy, carbonyl, allyl, halogenated alkyl groups, and (Ri) Ri, R'i of m, (R'i) n is a hydrogen atom, a halogen atom or an alkyl or alkoxy group having 2 to 5 carbon atoms as the same kind or different substituents, and m, n is 1 to 4 representing the number of substituents an integer, X ^- is an anion such as a halogen atom, perchloric acid, alkyl sulfonic acid, toluene sulfonic acid, Y is a nitrogen atom having an oxygen atom or an alkyl group).

The cyanine-based pigment of the general formula (I) used in the present invention has a methine chain, for example, can be illustrated as the following formula (I-1, I-2, I-3).

Examples of the cyanine-based pigment of the general formula (II) used in the present invention may be exemplified as the following formulas (II-2, II-2, II-3).

The optical recording medium of the present invention can be manufactured from disks and tapes, and when the disks are to be manufactured, the above general formula (1) may be applied to a substrate 1 such as polycarbonate (PC) or polymethyl methacrylate on which pregrooves are formed. Dissolve the pigment of I) or (II) at 1 to 5wt% in methyl cellosolve (MC; 2-methoxyethanol) or co-solvent such as MC / MeOH, MC / BuOH, etc. It is coated with -3000 to produce a recording layer 2 of 0.05 to 0.2 mu m. Here, sputtering with Au, Au-Pd alloy, Al, etc. forms a reflective layer 3 of 500 to 1000 mW, and a protective layer 4 of 5 to 15 µm is formed thereon to form a disc. The recording layer 2 can be recorded and reproduced only when the recording layer 2 is 0.05 to 0.2 µm. If the recording layer 2 is larger than the above, the reflectance decreases so that the recording data cannot be detected. If the recording layer 2 falls below, the reflectance is improved but the recording becomes difficult.

When the optical recording medium of the present invention is to be produced in a tape, a pigment of the general formula (I) or (II) and polyvinyl alcohol (PVA) are coated on a 30 μm polyethylene terephthalate film (PET film) on which Al is deposited at 0.05 μm. ), Polycarbonate (PC), polyvinylacetate (PVAc) and the like dissolved in toluene or cyclohexanone to a coating layer of 0.05 ~ 0.3㎛ thickness to form a recording layer, the silicone hard protective layer over 0.1 ~ 0.3㎛ Coating to prepare the tape of the invention. The addition of the polymer to make the recording layer is to increase the adhesive force to the metal deposition surface of the tape, the recording layer during the tape manufacturing so that the weight ratio of the dye to the combined amount of the pigment and polymer 25 to 85wt% If it is more than this, the adhesive force with a board | substrate will fall, and below it, the recording characteristic will fall. In addition, it is preferable that the concentration of the dye in the solvent only is 0.5 to 5 wt%. If it exceeds the reference value, it becomes a factor of cost increase.

In the present invention, the cyanine-based pigment is composed of short methine chains as in the general formula (I) or (II), which is easier to synthesize than conventional pigments, and is advantageous in manufacturing process and cost, and has good light resistance and short wavelength. This increases the recording density. This is a recording laser of 5.25 inch (13.3 cm) optical disc. When using a light source of 780 or 830 nm, the recording capacity is 500 MB and a moving image can be recorded for about 10 minutes. However, the present invention uses a short wavelength (for example, 532 nm) for CAV. If you adjust the rotation speed by (Constant Angle Velocity) method to 4.2 GB and CLV (Constant Linear Velocity) method, you can record up to 55 minutes of moving images up to 6.3 GB.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 (a) is a cross-sectional view of the organic optical recording medium used in the present invention, which is composed of a substrate 1, a recording layer 2, a reflective layer 3, and a protective layer 4 on which pregrooves are formed. When the laser is focused on the recording layer 2 during recording, the dye in the recording layer 2 absorbs the laser and generates heat. Due to this heat, the substrate 1 is partially melted and mixed with the deteriorated pigment, and recording is formed as a mixture of bumps in the recording layer 2 in the pregroove portion of the substrate 1 as shown in FIG. 1 (b). When the recording is played back, the recording laser is used, and the reading is performed at a lower output than the recording time. When the laser is irradiated to the surface of the disc, the information is read by the difference in reflectance between the recorded portion and the non-recorded portion.

2 is a light source structure used in the present invention, which uses a laser diode 10 of Spectra Diode Rubber, which can produce 500 mW at 809 nm, and focuses it on the lens 11 and the mirror 12 and then shortens the wavelength. In order to pass the NdYAG laser (13) of the Russian Polyus Research Institute (Laser Compact Co., Ltd.), which absorbs 809 nm wavelength and emits 1024 nm light, the second harmonic oscillator KTP (KTiOPO ₄ ) laser 14 is again used. By using a short wavelength light source of 532nm possible up to 25mW. 15 is a Brewster plate, 16 is an output mirror, 17 is a beam splitter, 18 is a color filter with a band filter function, and 19 is an output of the laser diode 10. It is a diode to sense.

Hereinafter, the present invention will be described in detail with reference to Examples, but the Examples do not limit the present invention.

[Examples 1-3]

After preparing the following cyanine dye (optional among NK-79, NK-1532, and NK-2610) of the Japanese photosensitive dye shown in Table 1 in a 4 wt% solution in a solvent, the rpm was applied to the PC substrate 1 on which pregrooves were formed. Coating to 2000 produces a recording layer 2 having a thickness of 0.07 mu m. Au was used as the reflective layer 3 at 1000 mu m, and the protective layer 4 was manufactured at 10 mu m using SD-17 manufactured by DIC of Japan. The optical recording disc thus obtained was recorded at an output of 8 mW and a speed of 1.4 m / sec using a recording device having a wavelength of 532 nm, and the C / N ratio at the time of reproduction was measured and shown in Table 1 below. The light resistance test was carried out using a Xe lamp 1.5KW and irradiated at a distance of 15 cm for 20 hours to confirm the change in reflectance. Temperature and humidity reliability was evaluated by C / N ratio change after standing for 24 hours at 70 ℃, 90% humidity conditions.

EXAMPLES 4-6

Prepared similarly to Examples 1 to 3, but the following cyanine pigment (alternative of NK-85, NK-86, NK-1420), polyvinylacetate and toluene shown in Table 1 on a 30㎛ film deposited with an Al reflective film 0.05㎛ Coating with a mixed solution in a ratio of 1: 1: 98 yields a recording layer of 0.1 mu m. Next, as a silicon-based hard protective layer, GE's As-4000 was prepared as a 25% solution in isopropyl alcohol (IPA) to prepare an optical recording tape coated at 0.15 μm, measured in the same manner as in Examples 1 to 3, and the characteristics thereof are shown in Table 1 below. Together.

TABLE 1

Claims (5)

In a write once read many (WORM) type recording medium in which a recording layer, a reflective layer, and a protective layer are formed on a substrate, the recording layer contains a cyanine-based dye represented by the following general formula (I) or (II) and is recorded in a short wavelength; An optical recording medium, characterized in that the reproduction. (In the formula (I) or (II), Z is an atomic group forming a benzene ring or a naphthalene ring, R ₁ , R ₂ is one of alkyl, alkoxy, hydroxy, carbonyl, allyl, halogenated alkyl groups, and (Ri) Ri, R'i of m, (R'i) n is a hydrogen atom, a halogen atom or an alkyl or alkoxy group having 2 to 5 carbon atoms as the same kind or different substituents, and m, n is 1 to 4 representing the number of substituents An integer such as a halogen atom, perchloric acid, alkylsulfonic acid, toluenesulfonic acid, and Y is an oxygen atom or a nitrogen atom having an alkyl group. The optical recording medium according to claim 1, wherein the short wavelength is a short wavelength laser light source of 550 nm or less. The optical recording medium according to claim 1, wherein the recording layer made of cyanine-based dye represented by the general formula (I) or (II) forms 0.05-0.2 탆, the reflective layer is 500-1000 GPa, and a protective layer made of UV curable resin. The optical recording medium, characterized in that the short-wavelength optical recording disk formed in sequence 5 ~ 15㎛. The optical recording medium according to claim 1, wherein a recording layer comprising a cyanine dye and a polymer represented by the general formula (I) or (II) is formed on a film on which a reflective film is deposited, having a thickness of 0.05 to 0.3 µm. The optical recording medium, characterized in that the hard protective layer is a short wavelength optical recording tape formed of 0.1 ~ 0.3㎛. The recording layer of the short wavelength optical recording tape is formed so that the weight ratio of the cyanine dye represented by the general formula (I) or (II) and the dye with respect to the total amount of the polymer is 25 to 85 wt%. Optical recording medium.