JPH02252143A - Erasable optical information recording medium and method for recording and erasing information - Google Patents

Abstract

PURPOSE:To obtain the recording medium which can be easily formed by incorporating a dyestuff having compability with a polymer which is reversibly changed by temp. to a required state into this polymer and heating the polymer, thereby controlling formation of the bump state. CONSTITUTION:The optical information recording medium which is optically homogeneous is formed by incorporating the dyestuff having the compatibility with the polymer which is in a resin state at a low temp. and is reversibly changed to a rubber state at a high temp. into this polymer. If The recording medium is irradiated with laser light which is oscillated at the wavelength corresponding to the absorption wavelength of the dyestuff, the irradiated spot is partially rapidly heated and cooled and the spot bump of the build up part is formed. The optical recording is thus executed. On the other hand, the spot bump attains the rubber state and diminishes when this bump is irradiated by the weak laser light and is thereby heated to the transition temp. and is then slowly cooled. The recording and erasing are thus executed. The erasable optical information recording medium is easily formed by using the org. solvent of the polymer without requiring a treatment, such as vapor deposition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel optical information recording medium J3 and a recording/erasing method thereof. More specifically, the present invention relates to an organic polymer/organic dye mixed recording medium that can efficiently record optical information and erase each recorded pitch by changing its shape when heated.

BACKGROUND TECHNOLOGY AND PROBLEMS Conventionally, many optical recording media using organic dyes have been proposed (for example, JP-A-61-163891.61268).
487, 62-56191. 62-122787.6
2-39286.6372594). Furthermore, many optical recording media using a combination of an organic dye and an organic polymer have been proposed (for example, JP-A No. 62-90291.
63-62794. 63191691>.

However, the recording principle of these recording media is that the recording medium undergoes an irreversible change in shape due to the heat generated when the dye absorbs light (mostly Rayleigh light) (in many cases, the recording medium changes its shape from piston to formation). ), making it extremely difficult or impossible to erase records.

In other words, in the case of a dye molecule-only medium, recording is performed by bit formation accompanied by vaporization and dispersion of the dye, so the lυ
It was impossible to erase the shadowed bits. In addition, in the case of a mixed system of polymer and dye, recording is performed by forming bits by flowing deformation of the polymer.
It was necessary to erase the data by heating the entire rack 1 to 1 containing the disc by laser beam irradiation and then slowly cooling it, or by heating and slowly cooling the entire surface of the recording medium. Another conventional technology (Japanese Patent Application Laid-Open No. 60-69846. 63136337
゜63-136338. 63-164042), the dome-shaped protrusion (
A recordable/erasable medium has been proposed that includes an expandable layer that forms bumps (bumps) and a retention layer that retains this shape. When recording on this medium, laser light is irradiated with the absorption wavelength (λ1) of the dye mixed in the expansion layer in advance so that the expansion layer forms a bump and the retention layer maintains this shape. .

In addition, when erasing recorded bumps, laser light is irradiated at the absorption wavelength (λ2) of the dye mixed in the retention layer in advance, and the retention layer is heated above its To, making it difficult to maintain the bump shape. Make it so that According to this disclosed method, recording and erasing can certainly be performed reversibly, but the following problems also occur. That is, there are problems such as a) the need for a three-wavelength laser for recording and erasing, b) the need for two types of dyes with different maximum absorption wavelengths, and C) the complicated layer structure of the recording medium.

In response to organic optical recording media that have these problems, recording and erasable recording media that utilize phase change of inorganic crystals in a thermal mode have been proposed. However, since these are inorganic materials, simple film-forming methods such as l-ting and casting cannot be used, and relatively complicated and expensive film-forming methods such as vacuum evaporation and sputtering cannot be used. No.

In view of these circumstances, the inventors of the present invention have conducted intensive studies on optical recording media that are soluble in organic solvents, can be coated, and are recordable and erasable, and have developed a polymer with the following thermal properties. The present inventors have discovered that a medium composed of an organic dye can serve as an optical information recording medium that does not have the above-mentioned problems, and have completed the present invention.

Summary of the present invention The optical recording medium according to the present invention comprises a polymer [P] that can reversibly change into a resin state at a low temperature and a rubber state at a high temperature, and a dye [D] that is compatible with the polymer [P]. An optically homogeneous medium containing dye [D], which is irradiated with strong laser light that oscillates at a wavelength corresponding to the absorption wavelength of the dye [D], to partially rapidly heat and cool the irradiated spot. It is a medium that can form protrusions (bumps) by heating the bumps to a rubbery state by irradiating them with weak laser light, and then gradually cool the bumps to reduce the bumps.

Further, the optical recording/erasing method according to the present invention includes (1) irradiating a strong laser beam oscillated at a wavelength corresponding to the absorption wavelength of the dye [D] in the medium, and the irradiated spora 1 Information is recorded by rapidly heating and cooling a portion of the surface to form a bump, and by irradiating weak laser light onto the /V shadow-forming lζ bump,
This process consists of heating and slowly cooling the bumps to a rubber state, and erasing information by reducing the number of bumps.

The principle of recording and erasing of the present invention will be explained in more detail with reference to the drawings. A recording medium (2) according to the present invention is placed on a transparent substrate (1).
) is formed (Figure a). Bumps (3) are formed on the medium surface and information is recorded by irradiating the medium with a laser beam that oscillates at the absorption wavelength of the dye [D] from the substrate side or the medium surface side (Figure b). To erase a record once written, the laser light intensity is lowered than when writing.
This is done by irradiating the bump so that the temperature of the irradiation part is slightly higher than l+ of the medium (Figure C). To reproduce recorded information, the surface of the medium is irradiated with a very weak laser beam that does not exceed T(1).
This is done by detecting the presence or absence of bumps and differences in shape as differences in foul rate.

Furthermore, if necessary, a reflective layer may be further provided on the medium layer surface and/or the substrate surface in order to increase the reflectance of the medium surface.

The substrate (1) used in the present invention is not particularly limited as long as it is transparent. Specific examples include polycarbonate, poly(ethylene terephthalate), poly(
Examples include methyl methacrylate) and glass plates.

The polymer [P] used in the present invention is one that transforms into a resin state at a low temperature and into a rubber state at a high temperature, and preferably has a transition temperature [T(l)] in the range of 60 to 150°C. When T (
If the temperature is higher than 150° C., it becomes difficult to slowly cool the medium during erasing records, resulting in poor recording and erasing characteristics. Furthermore, a crosslinked structure is introduced into the polymer [P] of the present invention as necessary in order to prevent irreversible flow deformation and formation of pimples due to laser beam irradiation. Polymer [P] exhibiting these properties is a medium in which soft molecular chains [or segment 1] exhibiting elastic properties at room temperature and hard molecular chains [or segment 1] exhibiting high elastic modulus are microdispersed. . Specific examples of suitable polymers [P] that have these characteristics (IiIII) include crosslinked oligomers or polymers derived from one or more monomers selected from rolobrene, butadiene, and isoprene; The crosslinking agent for 1 polymer [P] can be selected depending on the type of polymer or oligomer used. For example, when using a polymer or oligomer having a hydroxyl group, the crosslinking agent can include crosslinked polyurethane. Polyfunctional isocyanes 1 to 1 are preferably used, and the crosslinking reaction is achieved by heat treatment.Also, vinyl groups and (meth)acrylate 1 are used as functional groups.
~J: Which radical polymerization pig, t! When using a polymer containing a polymer, the crosslinking reaction can be achieved by heating or irradiating with light in the presence of a polymerization initiator. The resin-rubber transition temperature of these polymers [P] is
It can be controlled by crosslinking density. The crosslinking density is controlled by experimentally determining the content of crosslinkable functional groups, the concentration of the crosslinking agent, and the crosslinking reaction conditions. As a method for forming a film of the polymer [P] thus obtained, when it is soluble in an organic solvent, a casting method or a spin coating method is used.

In addition, if the material is insoluble or poorly soluble in organic solvents, it can be formed into a film by heating and melting. The preferred thickness of the film is 0.1~
A range of 5 μm1, more preferably 0°2 to 2 μ7n, can be adopted.

As the dye [D] used in the present invention, any dye that has a high affinity for the polymer [P] and is stable against heat and laser light can be used.

Preferred specific examples of the dye [D] include phthalocyanine,
Examples include polymethine dyes represented by naphthalocyanine, nano-1 to quinone, nickel dithiol complex, and cyanine. Among these, particularly preferable dyes are phthalocyanine derivatives and naphthalocyanine derivatives soluble in organic solvents in which the aromatic nucleus is substituted with an alkyl group, aryl group, or aryloxy group having 2 to 20 carbon atoms, and phthalocyanine derivatives and naphthalocyanine derivatives in which the central metal has 2 to 20 carbon atoms. Naphthalocyanine derivatives substituted with alkyloxy, alkylsiloxy, or arylsiloxy groups and soluble in organic solvents. These dyes are mixed with polymer [[)1 to constitute the recording medium of the present invention. The mixing ratio of the dye [D] to the polymer [P] is not particularly limited, but the weight ratio of [D] to [P] is preferably 2 to 50%.

When recording optical information using the recording medium of the present invention, as described above, the laser beam irradiation is performed so that the temperature reaches the resin->rubber transition temperature of the polymer [P] constituting the recording medium. This process produces bumps on the surface of the medium, and the shape of the bumps is maintained through the subsequent rapid cooling process. In addition, when erasing the bumps (information) formed by the above method, irradiation with laser light is performed at a temperature slightly higher than the resin->rubber transition temperature of the polymer [P] constituting the medium. The subsequent slow cooling process reduces the bumps and erases the information. The laser light source used for recording information depends on the dye [D] used, but when using a near-infrared dye, for example, a gallium/substrate semiconductor laser can be used, and when using a visible light-absorbing dye, a , helium neon lasers, argon lasers, ruby lasers and dye lasers can be used. When recording information, these lasers have an output of 5 to 3077 LW, preferably 7 to 20 LW.
Irradiate for 5-0.1 μsec at mW. If the laser irradiation conditions are milder than the above range, recording will be insufficient, and if the laser irradiation conditions are more severe than the above range, the medium will undergo flow deformation, making subsequent erasing impossible. On the other hand, when erasing information, the above laser beam is irradiated with an output of 1 to 10 TrLW, preferably 3 to 7 TrLW, for 0.1 to 20 μs.

As described above, the recording method of the present invention uses polymer [P]
The basic principle is to use the unique thermal characteristics of the light to read changes in reflectance due to the formation and disappearance of bumps at the light irradiation area. Therefore, the recording medium of the present invention is reversible because it does not involve evaporation of the dye in the recording area or mlll loss.
Erasable. Furthermore, since the recording medium of the present invention can be easily formed into a film by any of spin coating, casting, and heating and melting, it also has an industrial advantage of being inexpensive.

In the following, the present invention will be explained in more detail according to examples.

Example 1 Liquid chloroprene rubber having a hydroxyl group at the end of the molecular chain [number average molecular weight: 5,100. Product name F H-050 (
Denki Kagaku Kogyo)] was mixed with polyisocyanate (trade name: Coronet 1-L (Nippon Urethane Kogyo)) so that the ratio of hydroxyl group/isocyanate group was -0.5, and the mixture was diluted 5 times with chloroform. In this solution, 1
0 parts by weight of soluble vanadyl phthalocyanine [trade name:
I RD-1001 (Nakamoto Chemical Synthesis)] was dissolved and the resulting solution was applied to the glass substrate F, and then the solvent was dried. Thereafter, the coating film was heat-treated in a dryer at 120° C. for 1 hour to carry out a crosslinking reaction of the polymer. Obtained Iζ
When the film was irradiated with a semiconductor laser beam with an oscillation wavelength of 830 nm and a leading output of IOMW as an IMH2 pulse signal, a clear bulge with a diameter of 1.5 μm (
The formation of bumps was observed. Subsequently, the same laser beam was applied to this recording spot using an output cuff TrLW of 0.2MH.
When irradiated with a z pulse signal, the bumps mentioned above had disappeared to such an extent that they could not be confirmed by microscopic observation. From this result, it was found that the above-mentioned recording medium could be an optical information recording medium capable of recording and erasing information.

Example 2 In Example 1, instead of using terminal hydroxylated chloroprene rubber, Niboran 125 (Nippon Urethane Kogyo), which is a hydroxyl group-containing polyether type elastomer, was used with the same functional group content as Ronate L (Nippon Urethane Kogyo). A crosslinked film was obtained in the same manner except that the combination (OH/NC0 = 1 > , when irradiated as a pulse signal of I M H2, a diameter of 1.2μ was formed on the surface of the medium.
Formation of a clear protuberance (bump) of m was observed. Continuing the bow, the same laser beam is emitted from the cuff onto this recording spot.
When irradiated with a pulse signal of mWr O, 2M l-1z, the above-mentioned bumps disappeared to such an extent that TJIr could not be recognized by microscopic observation. From this result, it was found that the above-mentioned recording medium could be an optical information recording medium capable of recording and erasing information.

Example 3 Instead of using crosslinked polyurethane in Example 1,
A polyurethane containing an acrylate group at the end of the molecular chain, trade name: Photocurable Resin 3052C (ThreeBond), was used, and soluble vanadyl phthalocyanine [IRD] was used.
After adding 10 parts by weight of IOol (Sansui Chemical Synthesis), a 5% solution was prepared in 10% form. After coating this on a glass substrate, the solvent was evaporated, and the resulting coating film was exposed to high-pressure mercury lamp light for 10 minutes in a nitrogen atmosphere to crosslink the polymer. A semiconductor laser beam with an oscillation wavelength of 830 nm and a leading output of 10 mW was applied to this product under the same conditions as in Example 1.
When irradiated with a MHz pulse signal, a clear bump with a diameter of 1.4 μm was observed to be formed on the medium surface. Subsequently, when this recording spot was irradiated with the same laser beam as a pulse signal of 0.2M1-12 with output cuff 'm and W, the above-mentioned bump had disappeared to such an extent that it could not be confirmed by microscopic observation.

From this result, it was found that the above-mentioned recording medium could be an optical information recording medium capable of recording and erasing information.

Example 4 Shape memory resin consisting of poly(styrene-butadiene) copolymer [trade name: Asmar (manufactured by Asahi Kasei ■)] 1 g, soluble vanadyl phthalocyanine [trade name: NIR-12 (manufactured by Sansui Gosei Kagaku)] 0 .3y and 26 g of toluene were mixed to form a homogeneous solution. After this solution was applied onto a glass substrate, the solvent was volatilized in a dry mold to form a film. A semiconductor laser beam having an oscillation wavelength of 830 nm and a leading output of 10 mW was applied to the film under the same conditions as in Example 1 at 1 M.
When the medium was irradiated with a l-IZ pulse signal, the formation of clear protuberances (bumps) with a diameter of 1.4 μm was observed on the medium surface. Subsequently, when this recording spot was irradiated with the same laser beam as a pulse signal of 0.2M+-12 with an output mW, the bumps mentioned above had disappeared to such an extent that they could not be confirmed by microscopic observation. From this result, it was found that the above recording medium can be used as an optical information recording medium that allows recording and erasing.

[Brief explanation of drawings]

The figure shows the principle of recording and erasing of the present invention.
1) is a transparent substrate, (2) is a recording medium, and (3) is a bump. Patent Applicant: Teijin Co., Ltd. Representative Patent Attorney Former 1) Written Amendment (Method) % Formula % 1. Indication of Case Patent Application No. 2003, Name of Invention Erasable Optical Information Recording Media and Information Recording/erasing method 3, Relationship with the person making the amendment Patent applicant: 1-6-7 Minamihonmachi, Chuo-ku, Osaka-shi, Osaka (300) Teijin Ltd. 4, Agent: 2-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo No. 1 (Iino Building) ke) Specification page 17, line 1] - line to line 13, "The figure...
It is... ” [Figure 1 shows the principle of recording and erasing of the present invention, (1) shows a transparent substrate,
(2) is a recording medium, and (3) is a bump. Among them, figure a has (2) formed on (1),
(3) By irradiating strong laser light onto figure a,
was formed. Also, Figure C shows the image irradiated with a weak laser beam. ” is corrected. (2) Correct the drawing as shown in the attached sheet. 5. Date of amendment order: July 4, 1999

Claims (5)

[Claims] (1) Optically homogeneous, comprising a polymer [P] that can reversibly change into a resin state at low temperatures and a rubber state at high temperatures, and a dye [D] that is compatible with the polymer [P]. It is an optical recording medium that is irradiated with a strong laser beam that oscillates at a wavelength corresponding to the absorption wavelength of the dye [D], and the irradiated spot is partially heated and cooled to form a raised part (
1. An optical recording medium in which bumps can be formed, and the bumps can be reduced by heating and slowly cooling the bumps to a rubber state by irradiating weak laser light. (2) The polymer [P] described in item (1) above does not exhibit flow deformation upon heating, and has a transition temperature from a resin state to a rubber state [glass transition point (Tg)] of 60 to 150°C.
The optical recording medium according to claim 1, wherein the optical recording medium is within the range of . (3) The optical information recording medium according to claim (1), wherein the polymer [P] described in item (1) above is selected from polyurethanes having a crosslinked structure. (4) The polymer [P] described in item (1) above is a crosslinked oligomer or polymer derived from one or more monomers selected from chloroprene, butadiene, and isoprene. Claim (1)
The optical information recording medium described above. (5) When recording information by irradiating the recording medium described in item (1) above, (i) a laser beam that oscillates at a wavelength corresponding to the absorption wavelength of the dye [D] in the recording medium; A process of recording information by irradiating the irradiated spot with a laser beam to form a raised part (bump) by partially heating and cooling the irradiation spot, and (ii) applying a weak laser beam to the bump once formed. A method for recording and erasing optical information comprising the steps of heating and slowly cooling the bumps to a rubber state by irradiation, and erasing information by reducing the number of bumps.