JPH07210899A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To prevent a leak of the component of a light absorbing layer to the outside while simplifying production by coating the light absorbing layer made of an org. coloring material and a reflecting layer on a substrate with a protective layer made of a prescribed compsn. CONSTITUTION:An absorbing layer 2 made of an org. coloring material, absorbing only light of a specified wavelength and changing its apparent reflectance and a reflecting layer 3 are laminated on a transparent substrate 1 and a protective layer 4 made of a compsn. fading the coloring material is formed on the layer 3. A color vanishing region 5 reaching the peripheral edge part of the substrate 1 while in contact with the layer 2 can be formed without removing the layer 2 and the objective optical information recording medium not leaking the component of the absorbing layer 2 to the outside is obtd. while simplifying production.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium such as an optical disk and an optical card.

[0002]

2. Description of the Related Art There is known a write-once type optical disk capable of recording only once in a sector or a track. The structure of such a write-once optical disc is shown in FIG. The substrate 1 is made of a transparent resin such as polycarbonate (PC) or polymethylmethacrylate (PMMA). A pre-groove (guide groove) for tracking a laser beam for recording information is formed on the transparent substrate 1 in advance. An organic dye light absorption layer 2 is formed on a transparent substrate 1, and a reflection layer 3 made of metal such as gold (Au) for optically enhancing a reproduction output level is further provided on the organic dye light absorption layer 2. A protective layer 4 such as an ultraviolet curable resin is provided on the top.

In this optical disk, a laser beam for writing and recording is irradiated from the transparent substrate 1 side toward the light absorption layer 2 and reflected by the reflection layer 3. At this time, since the organic dye light absorbing layer 2 has a property of absorbing light of a specific wavelength, the organic dye light absorbing layer 2 is heated by irradiation with a laser beam of a specific wavelength to melt the organic dye light absorbing layer 2 and absorb the light. The substrate 1 in close contact with the layer 2 is also heated. Here, the substrate 1 reaches the glass transition and softens. At this time, the dye is decomposed and pressure is applied to the interface between the substrate 1 and the light absorption layer 2. The materials of the dye and the substrate are mixed at the interface, and the interface is finally deformed. The pit portion formed by cooling the deformed portion apparently has a lower reflectance than the other reflection layer portions due to the phase difference of the laser beam. In this way, additional writing is completed on the light absorption layer 2. By utilizing this change in reflectance, the presence or absence of this pit portion is made to correspond to a binary value of 1 or 0, thereby performing recording / reproduction of the optical disc.

As shown in FIG. 1, the light absorbing layer is formed on the entire surface of the disk by a spin coating method, but the outer peripheral edge of the light absorbing layer is removed and each layer is covered with a protective layer. This is done in order to prevent the organic dye from leaking out from the outer peripheral edge of the disk and to prevent the organic dye from contaminating the disk surface. In order to form such a structure, there is known a technique of removing the peripheral edge of the light absorption layer with a special device and a solvent, or cutting with a special device having a cutting tool (JP-A-3-203835 and JP-A-3-203835). 203
836).

[0005]

However, the conventional method for removing the peripheral portion of the light absorbing layer requires not only a special device but also increases the number of disk manufacturing steps and complicates the process. In addition, the splash of solvent and the scattering of dust are inevitable, and the yield of disks cannot be improved even if a suction device is used. The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical information recording medium which simplifies the manufacturing process and does not leak the light absorbing layer component to the outside.

[0006]

An optical information recording medium of the present invention comprises a transparent substrate, a light absorbing layer made of an organic dye formed on the substrate, and a reflecting layer formed on the light absorbing layer. And a protective layer formed on the reflective layer while being in partial contact with the light absorbing layer, the optical information recording medium comprising a dye fading composition for decoloring the organic dye. And

[0007]

According to the present invention, it is possible to obtain an optical information recording medium which does not require a special device, simplifies the manufacturing process, does not leak the components of the light absorption layer to the outside, and is free from the disc substrate. .

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a partially enlarged cross section of the write-once optical disc of the embodiment. As shown in the figure, such an optical disc has a transparent substrate 1, a light absorbing layer 2 made of an organic dye formed thereon, a reflective layer 3 formed thereon, and a protective layer 4. The light absorption layer 2 extends to the outer circumference of the disc, and the outer peripheral edge portion thereof is not removed. The protective layer 4 is composed of a dye fading composition that decolorizes the organic dye, and is formed on the reflective layer 3 while partially contacting the outer peripheral edge of the light absorbing layer. Therefore, the organic dye and the dye fading composition are used. The color-erasing area 5 is formed on the outer peripheral portion of the disk by the reaction with the.

Such a dye fading composition has a hydrogen abstraction of at least one selected from the group consisting of (a) an unsaturated double bond-containing compound composed of an acrylic ester, (b) a benzophenone compound, an anthraquinone compound and a thioxanthone compound. An ultraviolet curable resin comprising a mixture of a type polymerization initiator and a (c) a polymerization accelerator comprising an amine.

Specifically, the unsaturated double bond-containing compound (a) composed of an acrylic ester used in the present invention can be roughly classified into a low molecular monomer and a polymer unsaturated group-containing resin. . Specific examples of the low molecular weight monomer include dicyclopentadieneoxyethyl (meth) acrylate,
Isoboronyl (meth) acrylate, 2,2-bis (4
-(Meth) acryloyloxyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxyphenyl) methane, trimethylolpropane tri (meth) acrylate, neopentyl glycol di (meth) acrylate, hydroxypivalic acid Neopentyl glycol di (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, dioxane glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) Of acrylate, trimethylolpropane tripropoxytri (meth) acrylate, dipentaerythritol hexa and penta (meth) acrylate, dipentaerythritol - it can be exemplified poly (meth) acrylate of caprolactone adduct, dimethylolpropane tetra (meth) acrylate of a (meth) acrylate monomers.

Specific examples of the polymer unsaturated group-containing resin include an epoxy (meth) acrylate obtained by reacting an epoxy resin such as a bisphenol A type epoxy resin or a novolak type epoxy resin with (meth) acrylic acid, Polyhydric alcohols such as neopentyl glycol, ethylene glycol, propylene glycol, 1,
6-hexanediol, trimethylolpropane, pentaerythritol, tricyclodecane dimethylol, bis- (hydroxymethyl) -cyclohexane and the like and polybasic acids such as succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, Polyester (meth) acrylate obtained by reaction of polyester polyol obtained by reaction with azelaic acid, tetrahydrophthalic anhydride, etc. and (meth) acrylic acid, or polyol such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. Polyether polyol, polyester polyol obtained by reaction of the polyhydric alcohol with the polybasic acid, reaction of the polyhydric alcohol with the polybasic acid and ε-caprolactone Caprolactone polyols obtained by, and polycarbonate polyols such as,
Polycarbonate polyols obtained by the reaction of 1,6-hexanediol and diphenyl carbonate and organic polyisocyanates, such as isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, and hydroxy. Urethane (meth) acrylate etc. which are obtained by reaction with a (meth) acrylate compound can be mentioned. Examples of hydroxy (meth) acrylate compounds include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and ε-caprolactone-β-hydroxyethyl (meth) acrylate adduct.

The benzophenone type of the hydrogen abstraction type polymerization initiator (b) includes benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, 4-hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-. There are methyldiphenyl sulfide and 3,3′-dimethyl-methoxybenzophenone. Further, as the thioxanthone system, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-isopropylthioxanthone. is there. Others include benzyl, camphorquinone and anthraquinoic acid.

As the polymerization accelerator (c), triethanolamine, methyldiethanolamine, triisopropanolamine, 4,4'-dimethylaminebenzophenone, 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4- Ethyl dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate,
4-Dimethylaminoacetophenone is used.

In this UV curable resin, the mixing ratio of each component is (a) 100 parts by weight of the unsaturated double bond-containing compound and (b) 0.05 to 20 parts by weight of the hydrogen abstraction type polymerization initiator. Parts, preferably 0.1 to 10 parts by weight, and 0.01 to 15 parts by weight of the (c) polymerization accelerator, preferably 0.05 to 7 parts by weight.

The organic dye light-absorbing layer 3 on the transparent substrate 1 contains a cyanine dye represented by the following formula (1),

[0016]

[Chemical 1]

A phthalocyanine dye or a mixture thereof is used. The light absorbing layer is formed on the entire surface of the disk by spin coating with such a dye, and the reflecting layer is formed thereon by vacuum deposition or sputtering. The outer edge of the light absorbing layer is not removed, and the outer edge of the light absorbing layer is covered with the decoloring region 5 generated by the reaction with the protective layer. Such a decoloring reaction is a reaction in which, for example, a methylene group, which is a binding group of the cyanine dye, is cleaved by the hydrogen-abstraction type polymerization initiator, and the dye absorption wavelength is changed by this, resulting in discoloration.

The substrate 1 is formed from a transparent resin such as PC or PMMA by injection molding or the 2P transfer method, and a pregroove for laser beam tracking servo is previously formed on the surface of the transparent substrate. The reflective layer 3 is made of Au, Ag, Cu,
It is made of a metal such as Al or an alloy thereof.

[0019]

As described above, according to the present invention, a transparent substrate, a light absorbing layer made of an organic dye formed on the substrate,
An optical information recording medium having a reflective layer formed on a light absorbing layer, comprising a dye fading composition for erasing an organic dye, and protecting formed on the reflective layer while partially contacting the light absorbing layer. Since the layer is provided, there is no need for a special device to remove the outer peripheral portion of the light absorption layer, the manufacturing process is simplified, the light absorption layer component is not leaked to the outside, and the optical information recording is not restricted by the disc substrate. The medium can be obtained.

[Brief description of drawings]

FIG. 1 is an enlarged partial sectional view of a conventional optical disc.

FIG. 2 is an enlarged partial sectional view of an optical disc of the present invention.

[Explanation of symbols]

 1 Substrate 2 Organic Dye Light Absorption Layer 3 Reflective Layer 4 Protective Layer 5 Decoloring Area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Hayashi 2680 Nishi Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Pioneer Video Co., Ltd. (72) Inventor Kenji Suzuki 2680 Nishi Hanawa, Tatomi-cho, Nakakoma-gun, Yamanashi Pioneer Video Co., Ltd. (72) Inventor Kazuhiko Ishii 1039 Kamiochiai, Yono City, Saitama Prefecture

Claims (3)

[Claims] 1. An optical information recording medium comprising a transparent substrate, a light absorbing layer made of an organic dye formed on the substrate, and a reflective layer formed on the light absorbing layer, wherein the organic dye is used. An optical information recording medium, which comprises a dye fading composition for erasing a colorant, and has a protective layer formed on the reflective layer while partially contacting the light absorbing layer. 2. The dye fading composition comprises at least one selected from (a) an unsaturated double bond-containing compound composed of an acrylic ester, (b) a benzophenone compound, an anthraquinone compound and a thioxanthone compound. 2. An optical information recording medium according to claim 1, which is an ultraviolet curable resin comprising a hydrogen-abstraction type polymerization initiator and a polymerization accelerator comprising (c) amines. 3. The ultraviolet curable resin comprises from 0.05 to 20 parts by weight of (a) an unsaturated double bond-containing compound and from 0.05 to 20 parts by weight of a (b) hydrogen abstraction type polymerization initiator. 3. A mixture of 1 to 10 parts by weight, and 0.01 to 15 parts by weight of (c) a polymerization accelerator, preferably 0.05 to 7 parts by weight. Optical information recording medium.