JP3008406B2 - Optical information recording medium and method of manufacturing the same - Google Patents

Description

Description: 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 a method for manufacturing the same, and particularly, for example, provided with a recording layer made of an organic dye-based heat mode recording material. The present invention relates to a suitable optical information recording medium using a WO (write-once) optical disk or the like and a method of manufacturing the same.

[Conventional technology]

At present, CDs (compact discs) are widely used for music reproduction, but these are only for reproduction, so-called DRs.
Since there is no AW (Direct Read After Write) function, the user cannot perform recording and editing. Therefore, the emergence of a CD having a DRAW function is desired. In addition, the realization of an inexpensive optical disk having a DRAW function is expected for optical disks other than CDs.

By the way, as an optical recording material having a DRAW function, a metal material such as a perforated Te-based metal material or a so-called phase-change In-based metal material that performs crystal-amorphous dislocation is considered promising, The formation of a recording layer using these metallic recording materials uses a thin film forming technique such as a vapor deposition method or a sputtering method, so that problems remain in terms of mass productivity and cost.

Therefore, a perforated (heat mode WO type) organic dye-based recording material that can use a spin coating method for film formation is considered more promising in terms of productivity.

As this type of optical information recording medium, there is a proposal to form a thin film of a dye such as squarylium or thiopyrylium on a transparent substrate made of polymethyl methacrylate resin or glass and to form pits by irradiating a laser beam ( Dj, 1 Gravesteijn et al., SPIE 420, 327, 1983).

In addition, cyanine dyes (JP-A-58-125246 and JP-A-59-85791) and naphthoquinone dyes (JP-A-58-224)
No. 793), an azurenium dye (JP-A-59-129954),
Numerous proposals have been made, such as naphthalocyanine dyes (JP-A-61-25886). In addition, there is a method in which light stability is improved by using a singlet oxygen quencher in combination with a cyanine dye (JP-A-59-67092). In each case, pits are formed on a recording layer consisting of a single dye layer to record information. It is to be recorded.

Further, a reflective layer is formed on a plastic film via a flattening layer, a recording layer made of a mixture of a dye and a polymer is formed thereon, and recording pits are formed by laser light irradiation (James W, Wheeler etal., SRIE 4
20, 39, 1983), or a recording layer formed of a mixture of a dye and a styrene oligomer (A. Kuroiwa et al.,
Jap. J. Appl. Phys. 22, 240, 1983), all of which record information by forming pits.

Further, in the hole-formed optical information recording medium, a recording layer is formed on a transparent substrate, and when a laser beam is irradiated, the irradiated portion dissolves the recording layer, and only the portion reduces the thickness of the recording layer. Alternatively, the substrate is exposed.

During playback, the reflectivity of only that part drops,
Although it can be read out as a signal, the difference between the reflectances of the unrecorded portion and the recorded portion is small, so that a sufficient degree of modulation cannot be obtained, which causes a reproduction error.

There is also known a method of recording information by forming bubbles by expanding a metal film by a vapor pressure generated by local heating of an organic film by laser light irradiation.

Conventionally, there is a recording method in which a recording layer is melt-expanded by a laser beam to form a pit. When this method was applied to a dye recording film, the decrease in viscosity with respect to dye and time was rate-determining, and good recording could not be performed. As a means to solve this problem, there is an example of using a thermally unstable dye and using a material which is efficiently affected by heat. However, it is not possible to improve the sensitivity at the time of recording with a thermally unstable material. On the other hand, it is possible, but at the time of reproduction, deterioration occurs due to the read light. In addition, even when a thermally unstable material was used, the pit shape only became large on the inner surface in a mortar shape, and a good pit shape with clear pit edges was impossible.

Dyes are generally unstable to light, particularly sunlight, and have the disadvantage of deteriorating the dyes.

[Problems to be solved by the invention]

By the way, it is necessary to provide a protective layer for protecting the recording layer in the optical disk, but it is desirable that the formation of the protective layer can be performed by a spin coating method in consideration of productivity and the like. In general, a protective resin is formed by spin-coating a system resin or the like.

However, when a material layer, a productivity, and a current mainstream UV-curable acrylate resin or the like having excellent characteristics are coated on the recording layer made of the above-described organic dye-based recording material, the recording layer is eroded, and the worst case occurs. In such a case, there is a possibility that the dye may be dissolved when the ultraviolet curable resin is coated, and may be completely washed away.

Conversely, when a recording layer made of a water-dispersible dye is formed on a substrate, the dye may be washed away when a thin layer made of a hydrophilic material is formed thereon.

In the case of using the various organic dyes as described above, in the case of the recording layer containing only the dye, the dye remains at the bottom of the pit formed by the irradiation of laser light, so that the irradiated laser light is reflected at that portion. Is done. Therefore, the difference in reflectance between the flat portion and the pit portion is small, and a sufficient degree of modulation cannot be obtained. Further, since the rim portion at the edge of the pit has a gentle and unclear shape, there is a problem that the rising of the signal output is not sharp.

Further, as described above, in the recording layer having the mixture of the dye and the polymer or the mixture of the dye and the styrene oligomer, the light absorption and the light reflection are lower than those of the recording layer of the dye alone, so The degree becomes lower. Furthermore, not only is the laser power required for laser light irradiation large, but also as in the case of the dye alone,
The pit shape is also unclear, and there is a problem in recording reliability.

In the conventional device, the signal is reproduced by utilizing the reflection of the surface of the metal film, and the metal film is formed by a thin layer forming technique such as an evaporation method or a sputtering method. Problems remain in terms.

Further, the conventional one has problems that the recording sensitivity is low and the light resistance is low.

As described above, in the conventional one, reliability, sensitivity,
There is a problem in terms of performance such as light fastness, and furthermore, there is a disadvantage that productivity is poor and production cost is high.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording medium which overcomes the above-mentioned drawbacks of the prior art, is excellent in performance, has good productivity, and is inexpensive to produce, and a method for manufacturing the same.

[Means for solving the problem]

In order to achieve the above object, a first aspect of the present invention is to provide a recording layer mainly composed of an organic dye on a translucent substrate directly or via an underlayer, and to form a hydrophilic polymer on the recording layer. After forming the thin layer, the thin layer is crosslinked or crystallized and subjected to a water-resistant and heat-resistant treatment.

In order to achieve the above object, a second present invention provides an optical information recording medium having a recording layer mainly composed of an organic dye provided directly or through an underlayer on a light-transmitting substrate. And a thin layer made of a water-insoluble hydrophilic polymer.

In order to achieve the above object, a third aspect of the present invention is to provide a recording layer mainly composed of an organic dye on a light-transmitting substrate directly or via an underlayer, and provide a water-insoluble hydrophilic high layer on the recording layer. After forming a thin layer composed of molecules by a spin coating method, the thin layer is crosslinked or crystallized and subjected to water and heat resistance treatment.

In order to achieve the above object, the fourth invention provides a recording layer and a thin layer covering the recording layer above a transparent substrate, and irradiates the recording layer with a radiation beam from the transparent substrate side or the side opposite to the substrate. And heating to form a cavity in the recording layer while deforming the thin layer substantially to the opposite side of the substrate, wherein the recording layer is made of a poorly water-soluble material. The thin layer is made of a hydrophilic material, and the thin layer is subjected to a water-resistant treatment by a polymerization reaction.

In order to achieve the above object, a fifth aspect of the present invention is directed to an optical information recording medium on which at least information is recorded using a laser beam, wherein a recording layer is formed on a substrate with or without an underlayer. Provided, the recording layer is capable of recording information on the recording layer by melting, expansion, decomposition, sublimation, etc.,
The recording layer has a temperature of 100 ° C. or higher and a laser beam power of 10 mW or less, at least a cyanine dye that melts, and an infrared absorber that absorbs in a wavelength region longer than the maximum absorption peak of the cyanine dye. It is contained at a ratio of 20% or less by weight to the cyanine dye,
Further, on the recording layer, a heat-deformable layer made of a water-soluble polymer crosslinked or crystallized and subjected to water resistance and heat resistance treatment is laminated.

The thin layer made of the above-described hydrophilic polymer of the present invention, since the recording layer made of an organic dye-based recording material is poorly water-soluble,
The film can be formed by a spin coating method with high productivity without affecting the recording layer at all. Here, the term "poorly water-soluble" means that it may be insoluble in water for a few seconds in a spin coating step of laminating a hydrophilic polymer, and may have slight solubility in water.

In addition, since this thin layer is hydrophilic and has low solubility in organic solvents, even if an ultraviolet-curable resin such as acrylate is formed as an overcoat layer on the thin layer, there is no effect on the thin layer. Without providing, the overcoat layer can also be formed by the spin coating method.

As described above, if the recording material in the portion of the recording layer irradiated with the laser beam is configured to be detached from the substrate side, the residual dye on the substrate surface is eliminated, and light reflection occurs effectively. Therefore, the shape of the recording pit becomes clear, and the rising of the output signal becomes sharp.

According to the present invention, as described above, by forming a signal cavity in the recording layer, the degree of modulation is increased by utilizing an optical interference effect as described in detail later, and a highly reliable optical information is obtained. A recording medium can be provided.

Furthermore, using an organic dye compound as a material of the recording layer,
An object of the present invention is to provide a method for manufacturing an optical information recording medium in which the productivity is improved and the manufacturing cost is low by forming a recording layer by applying this over a transparent substrate by spin coating.

In order to form a clear pit by irradiating the recording layer with a laser beam, it is necessary to decompose, sublime, and melt in a low temperature range. Therefore, it is preferable that the dye is thermally unstable at 230 ° C. or lower, and if it exceeds 230 ° C., high sensitivity cannot be achieved. The lower limit is 100 ° C., which corresponds to a temperature slightly higher than the maximum temperature in a car parked under the scorching sun in summer, and this temperature needs to be the limit temperature. The upper limit of 230 ° C. is a temperature suitable for satisfying recording conditions of a write power of 10 mW or less, a linear velocity of 6 m / s or more, and a write pulse width of about 100 nsec. However, there are inconveniences in terms of increase of the laser beam, durability of laser light, cost and the like.

When the linear speed is low, there is a problem in the transfer speed and the like. When the write pulse width is high in relation to the linear velocity, the recording capacity is reduced with a long pulse width. Therefore, although there is a relationship with the linear velocity, about 100 nsec is suitable.

In order to form pits efficiently, it is possible to form pits in a short time by expanding three-dimensionally instead of expanding the molten dye in the plane. For this purpose, a heat-deformable layer obtained by crosslinking or heat-treating a hydrophilic polymer is provided on the recording layer, receives heat from the recording layer during laser beam irradiation, and protrudes to the opposite side of the substrate, causing the dye to become three-dimensional. To expand.
At this time, the pressure inside the heat deformable layer simultaneously rises due to decomposition and sublimation of the dye, and the listing of the pressure promotes the formation of pits. Further, the physical properties of the material used for the heat deformable layer need to be water resistance and durability.

Since a water-insoluble cyanine dye is generally used, if a hydrophilic polymer is used for the heat-deformable layer material, the recording layer will not be disturbed during lamination. However, since it is hydrophilic, it deforms and expands by absorbing moisture in the air. For this reason, water resistance and temperature resistance are improved by performing a crosslinking treatment by adding a crosslinking agent, a heat treatment, a radiation treatment, or the like.

The improvement in the read light resistance will be described below. Read light degradation has two factors: degradation by laser heat and degradation by light. In order to suppress the thermal deterioration, heat is transmitted to the heat deformable layer by providing the heat deformable layer, heat accumulation is reduced, and deterioration is suppressed. In addition, regarding photodegradation, by adding an infrared absorber that shows absorption in a longer wavelength region than the maximum absorption peak of the cyanine dye to the cyanine dye,
The cyanine-based dye changes to a stable energy state, and light degradation can be suppressed. However, if the weight ratio exceeds 20% with respect to the cyanine dye, the stability also affects the recording sensitivity, and the high sensitivity is impaired.

〔Example〕

 Hereinafter, the present invention will be described with reference to the illustrated embodiments.

Embodiment 1 FIG. 1 is a schematic cross-sectional view of an essential part of an optical disc according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a disc-shaped substrate made of a translucent material, which can be made of a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy, or a transparent ceramic such as glass. In this embodiment, a polycarbonate substrate is used. 1a is the substrate 1
Center hole.

Reference numeral 2 denotes a recording layer formed on the substrate 1 by a spin coating method, which is made of a hardly water-soluble organic dye-based heat mode recording material. As the organic dye-based heat mode recording material, for example, polymethine dye, anthraquinone dye, cyanine dye, phthalocyanine dye, xanthene dye, triphenylmethane dye,
Pisolium-based dyes, azulene-based dyes, metal-containing azo dyes, and the like can be used. In this example, a cyanine dye material was used, and a methanol solution of this cyanine dye was used.
The recording layer 2 was formed on the substrate 1 by spin coating. The poor water solubility of the recording layer 2 means that the recording layer 2 is insoluble in water for a few seconds during spin coating of a thin layer made of a hydrophilic polymer and has a slight solubility in water. It doesn't matter.

Numeral 3 is a thin layer made of a hydrophilic polymer formed on the recording layer 2 by a spin coating method. For example, a water-soluble polymer shown below can be used.

1. Polyvinyl alcohol 2. Polyethylene oxide 3. Polyacrylic acid 4. Sodium polystyrene sulfonate 5. Polyvinylpyrrolidone 6. Polymethacrylic acid 7. Polypropylene glycol 8. Methylcellulose 9. Polyvinyl nitrate In this example, the thin layer 3 Polyvinyl alcohol (PVA) is used as a material, and an aqueous solution of the PVA is spin-coated to form a thin layer 3 having a thickness of 120 nm.

Note that the thickness of the thin layer 3 should be 40 nm (0.04 μm) or more. If the thickness is less than 40 nm, pinholes are generated, and water or foreign matter passes through the pinholes and enters the recording layer 2. Attach and cause an error. When an overcoat layer is further provided on the thin layer 3, the overcoat material penetrates through the pinhole and invades the recording layer 2. Therefore, it is desirable that the thickness of the thin layer 3 be 40 nm or more. On the other hand, the upper limit of the film thickness of the thin layer 3 is arbitrary, but when applied to an optical disk for CD, the thickness of the
The thickness of the thin layer 3 is limited to 400 μm or less because the thickness is currently defined as ± 0.1 mm and the total thickness of the disk is 1.1 to 1.5 mm. Of course, it can be 400 μm or more for applications other than CD. The adjustment of the film thickness of the thin layer 3 can be arbitrarily made by selecting the rotation mode of the substrate 1 when spin-coating the PVA, the dropping conditions, the solution concentration, and the atmosphere around the turntable.

Incidentally, since the thin layer 3 is made of a hydrophilic polymer such as PVA, the moisture resistance deteriorates. For this reason, the thin layer 3 is provided with water resistance (moisture resistance and moisture permeability) and heat resistance by a crosslinking treatment or the like. Specifically, a crosslinking agent or the like is added to an aqueous solution of a hydrophilic polymer to form a thin layer 3, and then a crosslinking reaction by light irradiation or a crosslinking reaction by heating is caused, or the addition of a crosslinking agent is performed. The thin layer 3 having no heat is crystallized by heat treatment (for example, modified PVA is used in this embodiment because PVA is used in this embodiment), so that water resistance and heat resistance can be imparted.

However, the above-mentioned crosslinking reaction by light irradiation, which does not require consideration of the thermal adverse effect on the substrate 1 and the recording layer 2,
Since the workability is also excellent, in this embodiment,
A method of adding chromium as a cross-linking agent and causing a cross-linking reaction of the thin layer 3 by light irradiation is employed.

The following are specific examples of the crosslinking means, and any means can be employed as needed.

1. Addition of, for example, copper, boron, aluminum, titanium, zirconium, tin, vanadium, chromium, etc. as an inorganic cross-linking agent 2. Acetalization using an aldehyde 3. Aldehylation of a hydroxyl group 4. Addition of an activated vinyl compound 5. Etherification by adding epoxy compound 6. Reaction of dicarboxylic acid under acid catalyst 7. Addition of succinic acid and sulfuric acid 8. Addition of triethyl glycol and methyl acrylate 9. Polyacrylic acid and methyl vinyl ether maleic The acid copolymer blend 4 is an overcoat layer formed on the thin layer 3 by a spin coating method. In this embodiment, an acrylate resin which is a UV-curable resin is used. Is set to The overcoat layer 4 may be made of a material other than the acrylate resin.

In this embodiment, after the thin layer 3 and the overcoat layer 4 are sequentially formed, both layers are irradiated with ultraviolet rays to crosslink the thin layer 3 and polymerize the overcoat layer 4.
Has water and heat resistance.

The optical disk manufactured as described above was subjected to a linear velocity of 1.25
When recording was performed with a recording power of 0.5 mW and recording was performed at a recording power of 0.5 mW, good recording / reproducing characteristics were obtained, and noise due to the existence of the intermediate thin layer 3 under the overcoat layer 4 was reduced. No increase was seen.

Further, since the thin layer 3 is hydrophilic, the material of the molten recording layer is easily repelled from the thin layer 3 during heat mode recording (during drilling of the recording layer 2), and good pits are formed. Was confirmed. The recorded pit row had a length of 0.9 to 3.3 μm and an interval of 0.9 to 3.3 μm.

Cyanine dyes include 1-methyl-2- [7-1 (1-
Using a 1.5% methyl alcohol solution of methyl 2-indolinidene) 1,3,5-heptatrienyl] 3,3-dibutyl-indolium-hexafluorophosphate, spin coating was performed on a polycarbonate substrate to form an 80 nm recording layer. Form.

Separately, a 10% aqueous solution of a mixture of polyvinyl alcohol having a saponification degree of 88.0% and a polymerization degree of 1,700 and 10% ammonium bichromate with respect to this is prepared. This solution is spin-coated on the recording layer to form a 60 nm thin layer. After drying this, 2.
UV irradiation is performed for 30 seconds at a distance of 4 KW and 15 cm to crosslink the above-mentioned polyvinyl alcohol, thereby producing an air sandwich type optical disk using an organic dye.

As a comparative example for this, sodium 2-acrylamide-2- described in JP-B-1-14879 is disclosed.
A 15% aqueous solution of methylpropanesulfonate polymer is prepared, and a 60 nm-thick film is formed on the recording layer of the organic dye to prepare an air sandwich type optical disc.

The recording characteristics of these optical disks were measured using a semiconductor laser having an oscillation wavelength of 830 nm and an objective lens having a numerical aperture of 0.53. The aforementioned optical disk was driven at 1800 rpm, and predetermined information was recorded with a pulse width of 100 ns and a recording power of 7 mW. As a result, the modulation degree of the optical disc according to the present invention in which the polyvinyl alcohol thin layer was provided on the cyanine dye recording layer was 80%, whereas the optical disc using the sodium 2-acrylamido-2-methylpropane sulfonate polymer was used. Was 49%.

When recording at a wavelength of 780 nm or 830 nm using a semiconductor laser as a light source, when a cyanine dye is used for the recording layer, it is optimal to use a crosslinked polyvinyl alcohol having a softening point of 200 to 230 ° C. as a thin layer material. . 200 ℃
When using a material having a softening point of less than
Optical recording with good N cannot be performed.

That is, in the present invention, the melting point or decomposition temperature of the cyanine dye used for the recording layer material is 200 to 230 ° C., and when the recording layer reaches this temperature by laser light irradiation, the recording layer fluidizes and vaporizes. In addition, swelling occurs in the portion of the thin layer corresponding to the laser spot, high C / N is obtained, and recording can be performed most preferably, particularly when the thin layer is formed of a material having a softening point of 200 ° C. or higher.

However, when a soft layer having a softening point of less than 200 ° C., such as sodium 2-acrylamido-2-methylpropane sulfonate, forms a thin layer, the portion irradiated with the laser beam melts the thin layer together with the recording layer to form a hole. It does not form a suitable bulge and does not provide high C / N.

In the present invention, in the semiconductor laser recording, the recording layer at the position irradiated with the laser beam, forming a suitable bulge, for the purpose of being able to record high C / N, strictly study the dye recording material, Furthermore, as a result of detailed studies on the material for the thin layer thereon, polyvinyl alcohol was determined as the most suitable material, and after forming a thin layer on the recording layer, this was crosslinked and subjected to a water resistant treatment. Made an optical disk.

Example 2 FIG. 2 relates to Example 2 of the present invention, in which an underlayer 5 for improving the sensitivity is provided on a substrate 1.

As a material of the underlayer 5, a self-oxidizing substance or the like is used. In this embodiment, polyvinyl nitrate which is one of the self-oxidizing substances is used, and an aqueous solution of polyvinyl nitrate is formed by a spin coating method. The base layer 5 is formed by forming a film. On this underlayer 5, a cyanine dye is dissolved in 1,2-dichloroethane,
The recording layer 2 is formed by spin-coating the solution. The thin layer 3 and the overcoat layer 4 are exactly the same as those in the first embodiment.

The optical disk according to the second embodiment has a linear speed of 1.25 m / sec,
When recording was performed with a recording power of 3 mW and reproduction was performed with a reproduction power of 0.5 mW, good recording / reproduction characteristics were obtained as in Example 1.

Embodiment 3 and Embodiment 4 FIGS. 3 and 4 show Embodiment 3 and Embodiment 4 of the present invention, respectively. In the third and fourth embodiments, the overcoat layer 4 is not provided. (Example 3 is a case without the underlayer 5, and Example 4 is a case with the underlayer 5). In the third and fourth embodiments, the thickness of the thin layer 3 is set to several tens to several hundreds of micrometers, and is subjected to a water and heat resistance treatment by a crosslinking reaction.
Also in this embodiment, similarly good recording / reproducing characteristics can be expected.

As described above, in each of the above-described embodiments, the thin layer 3 can be formed on the recording layer 2 made of the organic dye-based heat mode recording material formed by spin coating without spin-coating. Therefore, the productivity is improved and the cost can be reduced.

In the above-described embodiment, the recording layer 2 is an organic dye-based recording material, but the hydrophilic polymer of the present invention can be applied as a thin layer formed on a recording layer adopting various other recording modes. It is.

In addition to CDs, it can be used for laser disks, various write-once types, read / write type (erasable) type optical disks, etc., and in some cases can be applied to optical information recording media other than optical disks. However, the present invention is not limited to the recording speed control method.

Fifth Embodiment FIG. 5 is a longitudinal sectional view of an air sandwich type optical disc according to a fifth embodiment of the present invention, and FIG. 6 is an enlarged sectional view of a main part of the optical disc.

In these figures, reference numeral 11 denotes a substrate on a disk made of a translucent material, which is a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy,
Alternatively, a transparent ceramic such as glass can be used. In this embodiment, a polycarbonate substrate is used. 11a is a center hole of the substrate 11.

Reference numeral 12 denotes a recording layer formed on the substrate 11 by a spin coating method, and is made of a hardly water-soluble organic dye-based heat mode recording material. As the organic dye-based heat mode recording material, for example, polymethine dye, anthraquinone dye, cyanine dye, phthalocyanine dye, xanthene dye, triphenylmethane dye,
A pyrylium-based dye, an azulene-based dye, a metal-containing azo dye, or the like can be used. In this example, a cyanine dye material was used, and a methanol solution of this cyanine dye was used.
The recording layer 12 was formed on the substrate 11 by spin coating.

Among cyanine-based organic dyes, indole-based cyanine dyes having the following general structural formula are particularly preferable.

General structural formula In the formula, the carbon chain for constituting the methine chain, C ₃
A C ₁₇ to C ₁₇ linear or multi-membered ring, wherein the hydrogen atom attached to the carbon atom is a halogen element, (R ″ may be substituted with a C _{1 to} C ₆ linear or aromatic ring).

A and A 'may be the same or different and each represents an aromatic ring, and the hydrogen atom attached to the carbon atom is-
_{I, B r, -Cl, -C} n H 2n + 1 (n = 1~22), - OCH 3, −NO ₂ , (R is a linear hydrocarbon chain or an aromatic ring).

B and B 'may be the same or different and -O
-, -S-, -Se-, -CH = CH-, or (R 'is CH _3, alkyl group of _{C 2 H 5, C 3 H} 7, C 1 ~C 4 such as C ₄ H ₉₎ represent.

R and R 'may be the same or different and C _1-
It represents an alkyl group of C _22, which may be substituted with a sulfonyl group or carboxyl group.

X represents for example anionic or I containing phosphorus element such as six hydrofluoric phosphoric acid ion PF _6, an anion such as ClO _4.

m and n are each an integer of 0 or 1 to 3, and have a relationship of m + n ≦ 3.

The method of forming the recording layer 12 with or without an underlayer on the disk substrate 11 may be a solution spin coating method, a vapor deposition method or a lamination method using Langmuir Prosette, and these methods may be appropriately combined. Is also good.

FIG. 7 is a view showing a typical example in the above general structural formula, and other examples may be used.

FIG. 8 is a view showing a typical example of A and A 'in the above general structural formula.

Each of the organic dyes shown in FIGS. 9 to 14 was dissolved in 1,2-dichloroethane at 1% by weight, and this solution was applied on a disk substrate made of polymethyl methacrylate by a spinner method to form a recording layer. Assembled an optical disk according to a conventional method.

From various experimental results, in FIG. 9 to FIG. 14, in the general structural formula, -CH = CH-CH = or That is, the heat resistance and the recording sensitivity of the recording layer can be improved.

A and A ′ in the above general structural formula are If so, the reflectance of the recording layer can be increased.

Further, B and B 'in the above general structural formula are (R ′ is a C ₁ -C ₄ alkyl group) can increase the solubility of the organic dye.

Furthermore, R and R 'in the above general structural formula are
With C ₄ H ₉ or C ₅ H ₁₁ , the reflectance of the recording layer can be increased.

Especially in general structural formula And A and A ' And B and B ' A cyanine dye in which R and R 'are C ₂ H ₅ and X is PF ₆ or I can be awarded because of its excellent heat resistance, recording sensitivity, reflectance and solubility.

 Next, 1-methyl-2- [7- (1-methyl-3,3-di
Ethyl-2-indolinidene) 1,3,5-heptatrieni
Indole consisting of -3,3-dibutyl-indolium
A cyanine dye, and iodine ion as an anion.
I, perchlorate ion ClO_FourAnd hexafluorophosphate ion
PF₆Are arranged respectively. Thermal weight of these various organic dyes
A quantitative analysis was performed, and the results are shown in FIG. Smell
I Is a dotted line, and ClO_Four One using
In the dotted line, PF₆ Is the solid line, and the weight is
The state of change was indicated.

The measuring instrument has a differential scanning calorimeter of TAS-100 manufactured by Rigaku Denki Co., Ltd., and is operated every minute in a nitrogen stream having a flow rate of 100 ml / min.
The sample was heated at a heating rate of 20 ° C., and the temperature at which the weight of the sample began to decrease was measured.

Next, conditions for forming a recording layer and the like by spin coating will be described.

FIG. 16 is a schematic sectional view of a coating apparatus. In the figure, 15 is a motor, 16 is a coating nozzle, 17 is a turntable on which the disk substrate 11 is placed, 18 is a coating apparatus main body, 19 is a coating liquid, 20
Is a pressurizing pump, 21 is a housing, through which the nozzle 16 penetrates, the periphery of the turntable 17 is shut off from the outside air by the housing 21, and the inside is kept almost completely airtight. I have.

Pigment or pigment composition concentration is 0.4% to 20.0% by weight
And If the concentration exceeds 20.0% by weight, the final film thickness becomes too large, and pit formation during recording does not proceed well.
If the concentration is lower than 0.4% by weight, defects such as pinholes will occur.

The number of rotations of the substrate 11, that is, the number of rotations of the substrate 11 for shaking off excess dye or dye composition, and solvent is 350
Adjusted to ~ 6500rpm. If the rotation speed is lower than 350 rpm, the centrifugal force is insufficient, and a difference in drying speed occurs between the inner circumference and the outer circumference of the recording layer 12, resulting in uneven film thickness. On the other hand, if it exceeds 6500 rpm, the film thickness becomes too thin and a desired film pressure cannot be obtained.

Further, the periphery of the turntable 17 is sealed, or in practice, the dye or its composition cannot be completely sealed because the dye or the composition thereof is dropped while the turntable 17 is being rotated. This allows
The airflow caused by rotating the turntable 17 can be reduced. This air flow is indicated by a dotted line in FIG. 16, and the generation state of the air flow is greatly affected by the length of the substrate 11 and the highest part 22 in the sealed state, and this length d is set to 1.5 times or less the diameter of the substrate 11. And In addition, by making the state of sealing or near sealing, the partial pressure of the solvent in the gas phase can be increased, and the wettability of the solution to the substrate 11 can be improved. This significantly improves the uniformity of the film. FIG. 17 shows a state in which the optical characteristics (reflectance and transmittance) of the prior art are varied in the radial direction when the device is sealed.

As can be seen from this figure, in the prior art, the variation in the optical characteristics was found to be ± 10% or more relative to the average value. However, according to this embodiment, the variation was ± 5% relative to the average value.
It can be: This has the advantage that uniform recording and reading characteristics can be obtained.

The spin coating time, that is, the rotation time of the substrate 11 after dropping the dye or its composition is set to 1 second or more. If the spin coating time is shorter than 1 second, the dye or its composition cannot be sufficiently diffused on the signal pattern forming surface.

If necessary, the spin coating can be set by changing the number of rotations in several stages. This is because a number of rotations suitable for uniform film formation and a number of rotations for the purpose of drying when the film formation is almost completed are required.
Thereafter, a two-stage rotation method of rotating at a higher speed than the one stage is used.

The drying conditions after spin coating are as follows:
The drying time at ℃ is 15 seconds or more.

If the product of the drying temperature and the drying time is smaller than this value, the drying becomes incomplete. If the product is too large, a problem such as thermal deformation occurs on the substrate.

In the step of dropping the dye or its composition, the rotation mode of the substrate and the like can be arbitrarily adjusted. For example, a stationary substrate is coated almost uniformly with a solution of the dye or its composition, and then the substrate is accelerated to a maximum rotation speed at a stretch, or a clamp is applied to a substrate already rotating at an appropriate rotation speed. A mode in which a solution of a dye or a composition thereof is dropped on the outer peripheral portion from the ping area can be adopted.

Returning to FIG. 6, reference numeral 13 in the figure denotes a thin layer made of a hydrophilic polymer material formed on the recording layer 2 by a spin coating method. For example, a water-soluble polymer as shown below may be used. it can.

1.Polyvinyl alcohol 2.Polyethylene oxide 3.Polyacrylic acid 4.Sodium polystyrene sulfonate 5.Polyvinyl pyrrolidone 6.Polymethacrylic acid 7.Polypropylene glycol 8.Methylcellulose 9.Polyvinyl nitrate Thermoplastic synthetic resins can also be used.

1. Polytetrafluoroethylene, polychlorotrifluoroethylene, vinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer Fluororesins such as tetrafluoroethylene-perfluoroalkylvinyl ether copolymers and tetrafluoroethylene-ethylene copolymers 2. Imide resins such as polyimide, polyamide imide, polyester imide 3.6-nylon, 11-nylon, 12-nylon, Amide resins such as 66-nylon, 610-nylon, and a mixture of 610-nylon and 66-nylon 4. Ethylene resins such as polyethylene, cross-linked polyethylene, ethylene-acrylate copolymer, and ionomer 5. Polypropylene 6. Styrene resin such as polystyrene, styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer 7. Polyvinyl chloride 8. Polyvinylidene chloride 9. Polyvinyl acetate 10. Polyvinyl acetal 11. Polycarbonate 12. Polyacetal 13. Polyethylene terephthalate , Polybutylene terephthalate or other saturated polyester resin 14. polyphenylene oxide 15. polysulfone Further, as the thin layer 13, the following rubbery material can be used.

1. Diene rubbers such as styrene-butadiene rubber, butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber, and chloroprene rubber 2. Olefin rubbers such as butyl rubber, ethylene-propylene rubber, acrylic rubber, chlorosulfonated polyethylene rubber, and fluoro rubber 3. Silicone rubber 4. Urethane rubber 5. Polysulfide rubber In this embodiment, polyvinyl alcohol (PVA) is used as the material of the thin layer 13, and an aqueous solution of the PVA is spin-coated to form a thin layer having a thickness of 120 nm. 13 are formed.

Incidentally, since the thin layer 13 is made of a hydrophilic polymer such as PVA, it has poor moisture resistance. Therefore, the thin layer 13 is provided with water resistance (moisture resistance, moisture permeability) and heat resistance by performing a cross-linking treatment or the like as described above.

Embodiment 6 Next, Embodiment 6 will be described. First, a polycarbonate substrate having a diameter of 130 mm was prepared by an injection molding method. Using a dye solution in which a cyanine dye having the molecular structural formula shown below was dissolved in methanol at 0.5% by weight, and applied to the substrate by spin coating, a recording layer was formed.

The spin coating conditions are as follows. 49
While rotating at 0 rpm, the above-mentioned dye solution is dropped into the center of the solution, rotated for 30 seconds, and further rotated at 3000 rpm for 30 seconds. For this spin coating, the coating apparatus shown in FIG. 16 was used. The capacity of the housing 15 was 5,000 cm ³ , and the housing was airtight, and the length d was 12 cm. After spin coating, drying was performed at room temperature for 30 seconds or more to form a cyanine dye recording layer on the substrate.

Next, as a thin layer material, polyvinyl alcohol is added to water.2.
5% by weight was dissolved, and 0.25% by weight of ammonium bichromate was added as a crosslinking agent to prepare a coating solution. This coating solution is dropped on the entire recording area of the substrate in a stationary state, and then the substrate is rotated at 2000 rpm for 20 seconds to remove excess liquid and further accelerated at 6000 rpm to promote drying.
Rotated for minutes. The coating apparatus shown in FIG. 16 is also used for this spin coating.

The thin layer thus formed was irradiated with ultraviolet rays to crosslink polyvinyl alcohol and to perform a water-resistant (moisture-resistant) treatment. In order to prevent the recording layer from being affected by ultraviolet rays, the thickness of the thin layer needs to be 40 nm or more.

Recording was performed at various powers with a pulse width of 220 nsec while rotating the optical disk obtained in this example at 600 rpm, and the results of measuring the modulation degree are shown in FIG. 18, where the modulation degree is the sensitivity of the recording layer. Where A represents the reflectance before recording and B represents the reflectance after recording, and is represented by the following equation.

Modulation degree = 1- (B / A) Curve A in the figure shows the characteristics of the present embodiment, and curve B shows the characteristics of the optical disk without a thin layer.

As is apparent from this figure, the recording sensitivity can be improved by forming a thin layer as in the present invention. The following can be considered as a reason for this. The dominant factor for forming pits in the recording layer is local melting and diffusion of the recording layer, but slight evaporation and sublimation occur simultaneously with melting. These vapors lose their escape due to the presence of a thin layer of polyvinyl alcohol, which increases the pressure in the enclosed space, and this pressure promotes diffusion to form good pits, which effectively increases the recording sensitivity. It is thought that it improves.

As can be seen from the results of the thermogravimetric analysis (see FIG. 15), the thermal behavior (eg, melting, evaporation, sublimation, etc.) of the recording layer depends on the material. The material used depends on the required recording conditions. For example, in order to record at a low power, it is preferable that the recording material be at least melted at 230 ° C. or less, which will be described later.

Also, the read power resistance is 0.5mW for read power.
In read count 10 ⁵ times, the deterioration of the light reflectance was very good and 0%.

(Embodiment 7) Fig. 19 is a diagram for explaining Embodiment 7 of the present invention. In the case of this embodiment, a single plate in which the recording layer 12, the thin layer 13, and the overcoat layer 14, the underlayer 15 and the like are formed on the substrate 11 is bonded to an adhesive such as an epoxy resin or an ultraviolet curable resin. The structure is such that they are integrally bonded via the layer 23.

(Eighth Embodiment) Fig. 20 is a diagram for explaining an eighth embodiment of the present invention. This embodiment shows an example in which a single plate in which a recording layer 12, a thin layer 13, an overcoat layer 14, an underlayer 15, and the like are formed on a substrate 11 is used alone.

FIG. 21 and FIG. 22 are enlarged sectional views near the recording pit. In the case of the recording pit shown in FIG. 21, the recording layer 12
A part of the thin layer 13 side is thinly left to form a cavity 24. On the other hand, in the case of the recording pit shown in FIG.
The thin layer 13 side is also almost completely melted to form a hole-shaped cavity 24. The difference between the shapes of the recording pits is determined by the material, the film thickness, the recording power, the irradiation time of the beam, and the like of the recording layer 12.

FIGS. 21 and 22 illustrate the case where a cavity is formed in the recording layer.However, the cavity is not necessarily formed in the recording layer due to radiation beam irradiation conditions and the like. It may bulge to the opposite side.

Example 9 Next, Example 9 will be described. 1-methyl-2-
[7- (1-methyl-2-indolinidene) -1,3,5-
Heptatrienyl] -3,3-dibutyl-indolium-
A 1.5% methyl alcohol solution of hexafluorophosphate (dye solution) is spin-coated on a polycarbonate substrate to form a 60 nm recording layer.

Separately, a 10% aqueous solution (thin layer forming solution) of a mixture of polyvinyl alcohol having a saponification degree of 88.0% and a polymerization degree of 1700, and 10% ammonium dichromate with respect to this is used. adjust. This thin layer forming solution is spin-coated on the recording layer to form a 60 nm thin layer.

After drying, ultraviolet irradiation is performed for 30 seconds at a distance of 15 cm from 2.4 KW to crosslink and cure the above-mentioned polyvinyl alcohol, thereby producing an air sandwich type optical disk using an organic dye.

The various conditions of the optical recording system for this optical disk are as follows. That is, a semiconductor laser having an oscillation wavelength of 830 nm was used, and an objective lens having a numerical aperture of 0.53 was used. The optical disk is rotated at 1800 rpm, and the pulse width is 100n.
s, information was recorded at a recording power of 7 mW. As a result, a modulation degree of 81% was obtained. Next, the formation state of the recording pit will be described. As described above, the optical information recording medium of the present invention is provided with a recording layer mainly composed of an organic dye on a transparent substrate, and a thin layer to be a pressure layer thereon. When the optical information recording medium is irradiated with laser light, the temperature of the recording layer locally increases, reaches a liquefied state and expands in volume, but the state of the thin layer on the recording layer does not change. Therefore, the recording layer is in a pressurized state, and the internal temperature further increases.
Due to this temperature rise, the recording layer is in a vaporized state, and the internal pressure further rises, causing the thin layer, which is the pressurized layer, to be deformed. No residual dye remains on the surface, and no effective light reflection occurs.

As described above, the thermal energy generated in the recording layer by the irradiation of the laser beam is prevented from being emitted to the outside by the thin layer provided thereon, and the energy is stored inside. This energy accumulation continues until the thin layer, which is the pressure layer, is pushed up and deformed, and the internal energy is reduced. In addition, the thermal energy of the laser irradiation unit is made uniform within the area and volume irradiated with the light, and the entire irradiation unit reaches a high temperature. For this reason, the dye material in the irradiated area is uniformly liquefied and / or vaporized, so that separation from the substrate surface is ensured.

The material mainly composed of the organic dye released from the substrate surface is redistributed in the thin layer as the pressure layer and / or absorbed and diffused into the thin layer.

FIG. 23 to FIG. 28 are schematic enlarged sectional views of recording pits when an optical information recording medium without an underlayer is used.

In the case of FIG. 23, the recording layer 32 of the portion irradiated with the laser beam
Disappears from the surface of the substrate 31, and the portion of the thin layer 33 corresponding to the disappeared portion is pushed upward substantially in a mountain shape.

In the case of FIG. 24, the thin layer 33 is pushed up as in the case of FIG. 23, but an annular ridge 34 is formed around the pushed up portion.

In the case of FIG. 25, the recording layer 32 of the portion irradiated with the laser beam
Disappears from the surface of the substrate 31, but the thin layer 33 is not deformed.

In the case of FIG. 26, the recording layer 32 of the portion irradiated with the laser beam
Disappears from the surface of the substrate 31, and an annular ridge 35 is formed around the disappeared portion. On the other hand, the thin layer 33 is depressed toward the disappeared portion.

In the case of FIGS. 27 and 28, the recording layer
Some of the 32 materials are redeposited. The recording layer 32 're-adhered to the inner surface of the thin layer 33 is in principle continuous with the recording layer 32, but may be separated from the recording layer 32 in some cases.

(Examples 10 and 11) FIGS. 29 and 30 are enlarged sectional views of an optical information recording medium showing Examples 10 and 11 of the present invention. No.
In the case of FIG. 29, an underlayer 36 is formed between the substrate 31 and the recording layer 32. In the case of FIG. 30, an overcoat layer 37 is further formed on the upper surface of the thin layer 33.

As a material of the underlayer 36, a self-oxidizing substance or the like is used, and in this embodiment, polyvinyl nitrate is used as the self-oxidizing substance.

As a material of the overcoat layer 37, for example, an acrylate resin or the like is used.

The following materials can also be used as the thin layer and / or the underlayer. For example, hydrocarbon resins,
Acrylic acid resin, vinyl acetate and vinyl alcohol resin, halogen-containing resin, nitrogen-containing vinyl polymer, diene polymer, polyether resin, polyethylene imine resin, phenol resin, amino resin, aromatic hydrocarbon resin, Ketone resin, polyester resin, polyamide resin, silicon resin, furan resin, polysulfide rubber, isoprene rubber, neoprene rubber, chlorosulfonated polyethylene rubber, acrylonitrile butadiene rubber,
Styrene-butadiene rubber, polybutadiene, polyurethane resin, polyurea resin, epoxy resin, oxidative polymerization type resin, esterified cellulose, etherified cellulose,
Carboxymethylcellulose sodium salt, carboxymethylcellulose ammonium salt, nitrocellulose resin, nitrocellulose oxide resin, protein resin, modified natural resin, fatty acid, fatty acid anhydride, chalcogenide metal or alloy or oxide, chalcogenite metal Other metals or alloys or oxides, alkyl silanes, alkoxy silanes, organometallic compounds using titanium elements, boron elements, aluminum elements instead of silicon, or hydrolysis products of these substances can be used. is there.

FIGS. 31 to 37 are schematic enlarged cross-sectional views of recording pits when the optical information recording medium shown in FIG. 29 is used.
Other configurations except for the underlayer 36 are the same as those shown in FIGS. 23 to 28, and thus description thereof will be omitted. In the case of FIG. 36, the recording layer 32 'reattached to the inner surface of the thin layer 33 is the recording layer 32.
In the case of FIG. 37, the recording layer 32 'is the recording layer
32 away.

(Examples 12, 13, and 14) FIGS. 38 to 40 are sectional views of optical discs according to Examples 12 to 14 of the present invention.

In the case of Example 12 shown in FIG. 38, the recording layer 32 on the substrate 31,
It has a structure in which recording veneers on which a thin layer 33 and the like are formed are integrally attached via an elastic layer 38 of, for example, polyurethane.

In the case of the thirteenth embodiment shown in FIG. 39, the structure is such that the recording single plate and the protection plate 39 are bonded together as described above. In addition, 40 in the figure is a void.

In the case of Embodiment 14 as shown in FIG. 40, the substrate 31 and the recording layer 32
And a reflective film 41 is provided between them, and a translucent protective plate 39 is used. 40 in the figure is a void.

Next, the optical interference effect of the optical information recording medium will be described with reference to FIGS. 41 and 42.

FIG. 41 is an explanatory diagram of the energy reaction rate R. Assuming that the amplitude reflectance when light travels from the medium 1 to the medium 2 is γ ₁₂ and the amplitude transmittance is t ₁₂ , the amplitude reflectance γ in the case of normal incidence
₁₂ , the amplitude transmittance t ₁₂ is obtained by using the refractive indices n ₁ and n ₂ of the media ₁ and ₂ .
It is represented by the following equation.

The energy reflectance R is represented by the following equation using the amplitude reflectance γ.

R = | γ | ² (3) That is, when the incident wave is a ₀ cos θ and the combined wave of the reflected waves is a ′ cos (θ + Δ), the energy reflectance R is represented by the following equation.

By utilizing this, the reflectance in each of the following states was calculated. FIG. 42 is a diagram for explaining a combined light of reflected light at each interface of an optical information recording medium in which a recording layer and a thin layer are sequentially formed on a substrate. Each signal in the figure is as follows.

PC: substrate made of polycarbonate dye: recording layer made of organic dye PVA: thin layer made of polyvinyl alcohol air: air (void) n ₀ : refractive index of air (n ₀ = 1) n ₁ : refractive index of PC (n ₁ = 1.6) N ₂ : refractive index of dye (n ₂ = 2.7) n ₃ : refractive index of PVA (n ₃ = 1.5) d ₁ : thickness of PVA d ₂ : thickness of dye A ₁ : interface between PC and dye A ₂ : Reflected light at the interface between dye and PVA A ₃ : Reflected light at the interface between PVA and air The reflected light A ₁ , A ₂ , A _{3 at} each interface can be represented by the following equation.

A ₁ = γ ₁₂ cosθ ……… (5) Therefore, the combined light (A ₁ + A ₂₎ of the reflected light A ₁ , A ₂ , and A ₃ at each interface
+ A ₃ ) Which can be represented by a'cos (θ + Δ).

Solving equation (8) = a'cos (θ + Δ), a ′ is converted to γ, t,
The energy reflectance R is represented by n, d, and λ, and the respective values are substituted and squared to obtain the energy reflectance R (because a ₀ = 1).

FIG. 43 shows an optical information recording medium shown in FIG. 42,
PVA thin layer and the thickness d ₁ of the wavelength λ of the incident light is fixed in a characteristic diagram showing changes in energy reflectance R in the case of sequentially changing the film thickness d ₂ of the recording layer.

FIG. 44 is a diagram for explaining a combined light of reflected light at each interface of an optical information recording medium in which only a recording layer is formed on a substrate.

The combined light (A ₁ + A ₂ ) in this case is expressed by the following equation in the same way as in the case of FIG.

FIG. 45 shows an optical information recording medium shown in FIG.
FIG. 7 is a characteristic diagram showing a change in energy reflectance R when the wavelength λ of incident light is fixed and the thickness d of the recording layer is sequentially changed.

FIG. 46 is a diagram for explaining a combined light of reflected light at each interface of an optical information recording medium in which a recording layer and a thin layer are sequentially formed on a substrate, and a cavity is formed in an intermediate portion of the recording layer. It is. Each symbol in the figure is as follows.

n ₀ : air and refractive index of the cavity (n ₀ = 1) d ₂ : thickness of the recording layer left between the PVA layer and the cavity d ₃ : thickness of the cavity d ₄ : thickness of the cavity The thickness of the recording layer left between the PC substrate A ₂ : Reflected light at the interface between the recording layer having the film thickness d ₄ and the cavity A ₃ : The interface between the cavity and the recording layer having the film thickness d ₂ reflection at light a _4: thickness reflected light a at the interface between the recording layer and the PVA layer having a d _{3 5:} reflected light a ₁ to a ₅ of the reflected light each interface at the interface of PVA layer and air, under It can be expressed by an equation.

A ₁ = γ ₁₂ cosθ ……… (10) Therefore, the combined light (A ₁ + A ₂ +) of the reflected light A _{1 to} A ₅ at each interface
A ₃ + A ₄ + A ₅ ) can be represented by the following equation (15).

FIG. 47 shows the optical information recording medium shown in FIG. 46,
Characteristic diagram showing the change in the energy reflectance R when the thickness d ₁ of the PVA thin layer, the thickness d ₂ and d ₄ in the recording layer and the wavelength d of the incident light are kept constant and the cavity thickness d ₃ is sequentially changed. It is. In the figure, when the values of d ₂ and d ₄ are reduced, the curve approaches the curve indicated by ●, and when the values of d ₂ and d ₄ are increased, the curve approaches the curve indicated by ▲.

FIG. 48 is a view for explaining a combined light of reflected light at each interface of an optical information recording medium in which a recording layer is formed on a substrate and a cavity is formed in an intermediate portion of the recording layer. Each symbol in the figure is as follows.

n ₀ : air and refractive index of cavity (n ₀ = 1) d ₁ : thickness of recording layer left between air and cavity d ₂ : thickness of cavity d ₃ : cavity and PC Thickness of the recording layer left between the substrate A ₂ : Reflected light at the interface between the recording layer having the film thickness d ₃ and the cavity A ₃ : At the interface between the cavity and the recording layer having the film thickness d ₁ of the reflected light a _4: reflected light a ₁ to a ₄ of the reflected light each interface at the interface of the recording layer and the air having a thickness d ₁ may be represented by the following equation.

A ₁ = γ ₁₂ cosθ ……… (16) Therefore, the combined light (A ₁ + A ₂ +) of the reflected light A _{1 to} A ₄ at each interface
A ₃ + A ₄ ) is represented by the following equation (20).

FIG. 49 shows the optical information recording medium shown in FIG. 48,
FIG. 7 is a characteristic diagram showing a change in energy reflectance R when the film thickness d ₁ and d ₃ in the recording layer and the wavelength λ of incident light are kept constant and the cavity thickness d ₂ is sequentially changed. In the figure, when the values of d ₁ and d ₃ are decreased, the curve approaches the curve indicated by the mark ●, and when the values of d ₁ and d ₃ are increased, the curve approaches the curve indicated by the mark ▲.

Since the recorded pits are read from the difference in reflectance between the unrecorded portion and the recorded pit portion, the modulation degree increases as the difference between the reflectance in the unrecorded portion and the reflectance in the recorded portion increases. Fig. 46,
The optical information recording medium in which the recording pits have a hollow shape as shown in FIG. 48 has a larger reflection than the optical information recording medium having a hole shape as shown in FIGS. 42 and 44. The difference in rates can be large. That is, a high degree of modulation can be obtained.

In FIGS. 46 and 48, the range of the film thickness of each part is as follows.

Film thickness d ₁ (PVA) of FIG. 46: 1 μm to 10 μm d ₂ (dye): 1 μm to 5 μm d ₃ (cavity thickness): 1 μm to 5 μm d ₄ (dye): 1 μm to 5 μm Thickness d ₁ (dye): 1 μm to 5 μm d ₂ (cavity thickness): 1 μm to 5 μm d ₃ (dye): 1 μm to 5 μm (Example 15) FIG. 50 shows another example of the recording pit according to the example of the present invention. It is an expanded sectional view which shows typically. As shown in this figure, depending on the material, physical properties, laser light irradiation conditions, and the like of the recording layer 32, the portion of the recording layer 32 mainly below the hollow portion 42 and the portion of the recording layer 32 above the hollow portion 42 are different. In some cases, a fibrous connecting portion 43 connecting the portions is formed.

Further, the cavity 42 is not limited to one bubble, and a plurality or a large number of bubbles may collectively form the cavity 42 in some cases.

As a means for reliably forming a cavity having a predetermined thickness, there is a method using microcapsules. That is, the micro-capsules are spinner-coated with the material of the recording layer to form an optical information recording medium, and then the film of the micro-capsules in the recording layer is evaporated or expanded by irradiating or heating the light to destroy the film. To form a cavity.
The inside of the microcapsule may be hollow, or may contain a self-oxidizing substance or the like.

As a specific example, polyvinyl nitrate is sealed inside, and a capsule is formed with a film made of a copolymer of gelatin and an anionic polymer.

(Example 16) Fig. 51 is an enlarged sectional view of an optical information recording medium showing Example 16 using microcapsules.

First, a polycarbonate substrate 51 having a diameter of 130 mm was formed by an injection molding method. Using a dye solution in which an organic dye having the following structural formula was dissolved in 0.8% by weight, the recording layer 52 was formed by coating the substrate 51 by spin coating.

The spin coating conditions are as follows.

While rotating the substrate at 490 rpm, the above-described dye solution was dropped at the center thereof, and then rotated for 30 seconds, and further 3000
Spin at rpm for 30 seconds. The volume around the turntable is 5
000 cm ³ and sealed.

Separately, an aqueous solution was prepared in which 2.5% by weight of polyvinyl alcohol and 10% by weight of ammonium bichromate were added. This aqueous solution was spin-coated on the recording layer 52.

In this case, the aqueous solution is applied substantially uniformly to the signal pattern forming surface of the substrate 51 while the substrate 51 is stationary.
Spin at 00 rpm, then spin at 6000 rpm for 30 seconds to shake off excess polyvinyl alcohol aqueous solution, the film thickness is 80 nm
Was formed. Next, this film was irradiated with ultraviolet rays for several minutes using an ultra-high pressure mercury lamp, and the polyvinyl alcohol was crosslinked with ammonium bichromate to form a thin layer 53.

By providing an air gap on the thin layer 53,
Can be easily deformed.

As a method of providing an air gap on the thin layer 53, microcapsules can be used. An example is shown below.

A microcapsule having a diameter of 10 μm is formed by enclosing polyvinyl nitrate inside and forming a capsule with a coating made of a copolymer of gelatin and an anionic polymer. The microcapsules were mixed in an aqueous solution of polyvinyl alcohol and applied to the thin layer 53 to a thickness of 100 μm to form a microcapsule layer 54.

On this microcapsule layer 54, an overcoat layer 55 made of an acrylate resin having a thickness of 100 μm is formed. Thereafter, the overcoat layer 55 was cured by irradiating ultraviolet rays, and at the same time, the microcapsules were broken to form an air gap layer having many bubbles.

(Example 17) Fig. 52 is an enlarged cross-sectional view of a main part of an optical disc according to Example 17 of the present invention.

In the figure, reference numeral 61 denotes a disk-shaped substrate made of a translucent material, which can be made of a transparent resin material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, epoxy resin, or a transparent ceramic such as glass. However, in this embodiment, a polycarbonate substrate is used.

62 is a recording layer formed by spin coating on the substrate 61, a cyanine-based dye that melts at least at 230 ° C. or lower, and an infrared absorbent that exhibits absorption in a wavelength region longer than the maximum absorption peak of the cyanine-based dye. It is composed of a mixture of 20% by weight or less with respect to the cyanine dye.

Among the cyanine-based organic dyes, indole-based cyanines having the following general structural formula are particularly preferable.

General structural formula In the formula, a carbon chain for constituting a methine chain, which is composed of a C _{3 to} C ₁₇ linear or multi-membered ring, wherein a hydrogen atom attached to a carbon atom is a halogen element, (R ″ may be substituted with a C _{1 to} C ₆ linear or aromatic ring).

A and A 'may be the same or different and each represents an aromatic ring, and a hydrogen atom attached to a carbon atom is -I,
−B _r , −Cl, −C _n H _{2n + 1} (n = 1 to 22), −OCH ₃ , −NO ₂ , (R is a linear hydrocarbon chain or an aromatic ring).

B and B 'may be the same or different, and -O-,
-S-, -Se-, -CH = CH-, (R ′ is a C ₁ -C ₄ alkyl group).

R and R 'may be the same or different and C _1-
It represents an alkyl group of C _22, which may be substituted with a sulfonyl group or carboxyl group.

X represents an anion such as I, PF ₆ and ClO ₄ .

m and n are each an integer of 0 or 1 to 3;
+ N ≦ 3.

The infrared absorber can be arbitrarily determined in relation to the dye, but in a specific example, the product names PA1001, PA1005, PA1006
Commercial products such as anthraquinone organic compounds such as (manufactured by Mitsui Toatsu Chemicals), polymethine organic compounds such as IR-820, and diimmonium organic compounds such as IRG-002 (manufactured by Nippon Kayaku) Can be used.

These absorbents are used for dyes such as cyanine dyes.
% Or less, and when forming a film, dissolve in a mixed solution of two or more types of solvents such as an alcohol-based solvent and water, an alcohol-based solvent and a solvent for a halogenated substance, or dissolve in an alcohol-based solvent. It is dissolved in a solution and spin-coated on the substrate.

The heat deformable layer 63 is made of a hydrophilic polymer formed on the recording layer 62 by a spin coating method. For example, the following materials can be used.

1. Polyvinyl alcohol 2. Polyethylene oxide 3. Polyacrylic acid 4. Sodium polystyrene sulfonate 5. Polyvinylpyrrolidone 6. Polymethacrylic acid 7. Polypropylene glycol 8. Methylcellulose 9. Carboxymethylcellulose 10. Polyvinyl nitrate Also, after the drying step, For example, a treatment for improving moisture resistance and moisture permeability, such as a crosslinking treatment of a hydrophilic polymer, can be performed.

 A specific example of this embodiment is as follows.

First, a substrate made of polycarbonate having a diameter of 130 mm was prepared by an injection molding method. The method for preparing the dye solution is as follows.

The following cyanine dye was dissolved in ethanol to prepare a solution having a concentration of 20% by weight.

Further, an infrared absorbing agent composed of 1% of a diimmonium-based organic compound with respect to the above dye (product name: IRG-0, manufactured by Nippon Kayaku Co., Ltd.)
02) was added and spin-coated to form a recording layer.

Thereafter, an aqueous solution in which 2.5% by weight of polyvinyl alcohol and 5% of ammonium bichromate with respect to polyvinyl alcohol were added was prepared. This solution was spin-coated to form a heat-deformable layer having a thickness of 60 nm.

The heat-deformed film formed as described above was irradiated with an ultraviolet ray for several minutes using an ultra-high pressure mercury lamp to crosslink polyvinyl alcohol and dichromic acid to form a complex of both.

The optical information recording medium created as described above is attached with an air gap provided so that the recording surface is disposed inside,
It was a double-sided optical disk.

Fig. 53 shows how recording was performed with various powers at a pulse width of 85nsec while rotating the optical disk thus produced at a rotation speed of 2400rpm and the modulation was measured. Is also shown.

As can be seen from FIG. 53, when the heat deformable layer is formed, a large degree of modulation can be obtained.

In addition, when the optical disk is read at a read power of 0.6 mW and a linear velocity of 6 m / s, the number of times the reflectance decreases by 10% in relative value is shown in Table 1 below.

Table 1 Number of sample readings A 1.0 × 10 ⁶ B 8.1 × 10 ⁵ C 2.5 × 10 ⁴ D 1.0 × 10 ³ A to D in the above table indicate the following items.

A: Example 17 (PVA + infrared absorber) B: No heat-deformable layer (infrared absorber only) C: No infrared absorber added (PVA only) D: No infrared absorber added, thermal deformation When there is no layer As is clear from Table 1, the number of readings of the sample according to Example 17 (sample A) is increased as compared with the other samples.

It has been found that in the optical information recording medium of the present invention, the thickness of the heat-deformable layer (thin layer) can be arbitrarily selected by optimizing the thickness of the recording layer. In particular, depending on the type of organic dye used for the recording layer, the thickness of the heat-deformable layer is 1 nm or more, and in the range of 1 nm to 4 nm, the heat-deformable layer can be raised and deformed with little energy, which is preferable. is there.

The relationship between the claimed invention, the purpose, the operation and effect, the embodiment, and the drawings is as follows.

(A) Inventions according to claims 1 to 3 (first to third inventions) Objective: To improve productivity and reduce production costs.

Function and effect: Since the recording layer made of an organic dye is poorly water-soluble, a thin layer made of a hydrophilic polymer can be formed by a spin-coating method with high productivity.

Since the thin layer has low solubility in the organic solvent, overcoating of the ultraviolet curable resin is possible.

Examples: Example 1 (FIG. 1), Example 2 (FIG. 2),
Example 3 (FIG. 3), Example 4 (FIG. 4), Example 5
(FIGS. 5 to 14), Example 6 (FIGS. 15 to 18, and Example 7 (FIG. 19)).

(B) Invention according to claim 4 (fourth invention) Object: To provide an optical information recording medium having good performance.

 Improve productivity and reduce production costs.

Function and effect: By forming a cavity in the recording layer, the degree of modulation can be increased by utilizing the optical interference effect.

A spin coating method with high mass productivity can be applied.

Example: Example 8 (FIG. 21), Example 12 (FIG. 38),
Example 13, (FIG. 39), Example 14 (FIGS. 40 to 49),
Example 15 (FIG. 50).

(C) Invention according to claim 8 (fifth invention) Object: To provide an optical information recording medium having good performance.

Function and effect: Since the cyanine dye is insoluble in water, even if a hydrophilic polymer is used for the thin layer, it does not adversely affect the tinting layer when forming the thin layer.

By adding an infrared absorber, photodegradation of the cyanine dye is suppressed.

Example: Example 17 (FIG. 52).

〔The invention's effect〕

As described above, according to the present invention, a thin layer that can be formed by a spin coating method with high productivity is also provided on a recording layer made of an organic dye-based recording material or the like to reduce the cost of an optical disc or the like having a DRAW function. Information recording medium and a method of manufacturing the same.

Further, according to the present invention, it is possible to provide an optical information recording medium in which the shape of the recording pit is clear, the rising of the output signal is sharp, and the reliability and sensitivity are high.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of an optical disk according to a first embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a main part of an optical disk according to a second embodiment of the present invention, and FIG. 4 is an enlarged sectional view of a main part of an optical disk according to a fourth embodiment of the present invention. FIG. 5 is a longitudinal sectional view of an air sandwich optical disk according to a fifth embodiment of the present invention. FIG. 6 is an enlarged sectional view of a main part of the optical disk, and FIG. 7 is a graph showing T in the general structural formula of the organic dye used in the embodiment.
FIG. 8 is a diagram showing a typical example of A and A ′ in the general structural formula, FIGS. 9 to 14 are diagrams showing specific examples of organic dyes according to Examples, FIG. 15 is a characteristic diagram showing the results of thermogravimetric analysis of the organic dye, FIG. 16 is a schematic cross-sectional view of a coating apparatus used in the embodiment, FIG. 17 is a characteristic diagram showing a variation state of optical characteristics due to a difference in coating technique, FIG. 18 is a modulation degree characteristic diagram of the recording layers of the embodiment of the present invention and the conventional one, FIG. 19 is a longitudinal sectional view of a bonded optical disc according to the seventh embodiment of the present invention, and FIG. FIG. 21 and FIG. 22 are enlarged cross-sectional views near recording pits, and FIG. 23 to FIG. 28 are recording pits on an optical disc according to Embodiment 9 of the present invention. FIG. 29 is a schematic enlarged sectional view of a main part of the optical disc according to the tenth embodiment of the present invention. 30 is an enlarged sectional view of a main part of the optical disc according to the eleventh embodiment of the present invention, and FIGS. 31 to 37 are schematic enlarged sectional views of recording pits on the optical disc according to the tenth embodiment of the present invention. FIG. 38 is a longitudinal sectional view of an optical disc according to Embodiment 12 of the present invention. FIG. 39 is a longitudinal sectional view of an optical disc according to Embodiment 13 of the present invention. FIG. 41 is an explanatory view of energy reflectivity, and FIG. 42 is an explanatory view of a composite light of reflected light at each interface of an optical information recording medium in which a recording layer and a thin layer are sequentially formed on a substrate. 43 is a characteristic diagram showing a change in energy reflectance when the thickness of the recording layer of the optical information recording medium shown in FIG. 42 is changed, and FIG. 44 is a diagram showing only the recording layer on the substrate. FIG. 45 is a view for explaining the combined light of the reflected light at each interface of the formed optical information recording medium, FIG. FIG. 46 is a characteristic diagram showing a change in energy reflectivity when a thin recording layer of an optical information recording medium is changed. FIG. 46 shows that a recording layer and a film thickness are sequentially formed on a substrate, and an intermediate portion of the recording layer is formed. FIG. 47 is a view for explaining the combined light of the reflected light at each interface of the optical information recording medium in which the cavity is formed. FIG. 47 shows a film thickness d ₂ in the recording layer of the optical information recording medium shown in FIG. a characteristic diagram showing changes in energy reflectance when sequentially changing the cavity thickness d ₃ and the d ₄ constant, FIG. 48 is formed only recording layer on a substrate, a cavity portion in an intermediate portion of the recording layer FIG. 49 is a view for explaining the combined light of the reflected light at each interface of the optical information recording medium on which is formed. FIG. 49 is a view showing the film thickness d ₁ , d in the recording layer of the optical information recording medium shown in FIG. characteristic diagram showing the change of the energy reflectance when _{the 3} sequentially changing a cavity thickness d ₂ in the constant, FIG. 50 is recorded according to the embodiment 15 of the present invention FIG. 51 is an enlarged cross-sectional view showing another schematic example of the pit. FIG. 51 shows an embodiment 16 using the microcapsule of the present invention.
52 is an enlarged cross-sectional view of a main part of the optical disc, FIG. 52 is an enlarged cross-sectional view of a main part of the optical disc according to Embodiment 17 of the present invention, and FIG. 53 is a modulation factor characteristic diagram with and without a thermally deformable layer. . 1,11,31,51,61 ... substrate 2,12,32,52,62 ... recording layer 3,13,33 ... thin layer 4,37,55 ... overcoat layer 5,36 ... bottom Geological layer 18 ... Applicator body 21 ... Housing 24,42 ... Cavity 63 ... Heat deformable layer.

──────────────────────────────────────────────────続 き Continuation of the front page (31) Priority claim number Japanese Patent Application No. 1-45300 (32) Priority date February 28, 2001 (Feb. 28, 1989) (33) Priority claim country Japan (JP) (72) Inventor Shinichiro Inuchi 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Inventor Hitoshi Watanabe 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Invention Person Hideo Fujiwara 1-1-88 Ushitora, Ibaraki-shi, Osaka, Japan Inside Hitachi Maxell Co., Ltd. (72) Inventor Kinutani 1-1-88 Ushitora, Ibaraki-shi, Osaka, Japan Hitachi Maxell Co., Ltd. (56) References JP 59-203252 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/24 G11B 7/26

Claims (5)

(57) [Claims] A recording layer mainly composed of an organic dye is provided directly or through an underlayer on a light-transmitting substrate, and a thin layer made of a hydrophilic polymer is formed on the recording layer. A method for producing an optical information recording medium, characterized in that a layer is crosslinked or crystallized and subjected to water resistance and heat resistance treatment. 2. An optical information recording medium having a recording layer mainly composed of an organic dye provided directly or through an underlayer on a light-transmitting substrate, wherein a water-insoluble hydrophilic polymer is formed on the recording layer. An optical information recording medium comprising a thin layer. 3. A recording layer mainly composed of an organic dye is provided on a light-transmitting substrate directly or through an underlayer, and a thin layer of a water-insoluble hydrophilic polymer is spin-coated on the recording layer. A method for producing an optical information recording medium, characterized in that after forming a film, the thin layer is crosslinked or crystallized and subjected to water and heat treatment. 4. A recording layer and a thin layer covering the recording layer are provided above the transparent substrate, and the recording layer is irradiated with a radiation beam from the transparent substrate side or the side opposite to the substrate to heat the recording layer. A method for manufacturing an optical information recording medium, wherein a cavity is formed in a recording layer while substantially deforming the recording layer on the side opposite to the substrate, wherein the recording layer is made of a poorly water-soluble material, and the thin layer is made of a new aqueous material. Wherein the thin layer is subjected to a water-resistant treatment by a polymerization reaction. 5. An optical information recording medium for recording at least information using a laser beam, wherein a recording layer is provided on a substrate with or without an underlayer, and the recording layer is melted and expanded. A recording layer capable of recording information by decomposition, sublimation, or the like, wherein the recording layer is at least 100 ° C. and within a laser beam power range of 10 mW or less, and at least a cyanine dye that melts; An infrared absorber exhibiting absorption in a wavelength region longer than the maximum absorption peak of the dye based on the cyanine dye at a weight ratio of 20% or less. An optical information recording medium comprising a heat-deformable layer made of a hydrophilic polymer which has been subjected to water resistance and heat treatment.