JP2959654B2 - Optical information recording medium - Google Patents

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 suitable for optical writing and recording using a laser or the like, and more particularly to an improved optical information recording medium used for an optical disk, an optical card and the like. .

[0002]

2. Description of the Related Art In recent years, as society has become more computerized, information recording media for recording or reproducing optical information, such as optical disks, optical cards, and optical tapes, and information recording have been developed as means for efficiently handling various types of information. -Many playback devices have been proposed. Some of the information recording media can detect binarized information by exchanging with a change in reflectance and a change in intensity of reflected light accompanying a change in surface shape such as the presence or absence of pits (holes).

As a recording medium based on a change in optical reflectance, a so-called heat mode recording material is used in which a recording layer is irradiated with an energy beam such as a laser beam in the form of a spot to change the state of a part of the recording layer for recording. Has been proposed.
These recording materials do not require development processing after writing information, and can be read directly after writing, so-called D
RAW [Direct Read After Write (di
correct reader write)] medium, capable of high-density recording, and capable of additional writing.

[0004] Also, there have been proposed many optical information recording media having a recording layer formed by a coating method using an organic dye having a relatively high reflectivity and a metallic luster. It is known that these organic dyes have a high reflectance near the absorption maximum wavelength and a large absorption coefficient. In particular, the polymethine dye appropriately selects a methine chain,
Since a recording film having a desired absorption maximum wavelength can be obtained by variously changing the conjugated aromatic ring portion, recording and reproduction can be performed by a semiconductor laser, and there is an advantage that the device can be reduced in size and cost can be reduced.

[0005]

However, the organic dye thin film has a problem that its reflectance is lower than that of the recording layer mainly composed of a low melting point metal such as Te. Further, a method of forming a metal reflection film on the organic dye absorbing layer to increase the reflectance has been proposed, but the thermal sensitivity of the adjacent metal reflection film is high, so that the recording sensitivity is deteriorated. was there. Furthermore, since vapor deposition is required at the time of forming the metal reflection film, there is a problem that the cost is increased.

Some organic dye thin film monolayers have a relatively high reflectance (25 to 40%). In this case, however, there is a drawback that the light absorption is reduced and the recording sensitivity is deteriorated. . Further, polymethine-based organic dyes used in organic dye thin films are generally liable to be oxidized or reduced in the presence of light or heat, resulting in reduced storage stability and reduced absorption coefficient and reflectance. Was.

For example, it is common to add a singlet oxygen quencher as a photooxidant to quench singlet oxygen generated by the excited triplet of the dye in order to prevent photobleaching of the dye due to oxidation. A proposal for adding the quencher to an organic color or the like is disclosed in JP-A-59-5579.
No. 4 and JP-A-59-55795. In these publications, various metal chelate complexes are mentioned as the quencher.

In order to prevent thermal oxidation deterioration and improve heat resistance, an antioxidant such as a hindered phenol compound, an arylamine compound, a thioether compound or a phosphite compound is added. And the proposal of adding such an antioxidant to an organic dye is disclosed in JP-A-59-213039.

On the other hand, in order to prevent photo-oxidation deterioration and improve weather resistance, an ultraviolet absorber such as a benzotriazole compound or a benzophenone compound, or a hindered amine-based compound having a light stabilization mechanism completely different from that of the ultraviolet absorber. It is also common to add a radical scavenging type light stabilizer such as a stabilizer, which is disclosed in JP-A-62-28291.

However, most of the polymethine dyes used in optical information recording media are cationic dyes, and thus are susceptible to reduction degradation by bases and the like.
The storage stability of the antioxidant alone is poor, and the absorption coefficient and the reflectance are reduced.

The present invention has been made in view of the above problems, and a first object of the present invention is to suppress the reducibility of an organic dye as a component of a recording layer in the presence of light or heat. ,
It is an object of the present invention to provide an optical information recording medium having good environmental preservation stability in which a decrease in contrast and reflectance is prevented.

A second object of the present invention is to use an organic dye to maintain a high sensitivity, a high C / N ratio and a low cost, a high reflectance, a high recording contrast, and an organic dye. It is an object of the present invention to provide an optical information recording medium having good environmental stability by suppressing the reducibility of the medium.

[0013]

That is, according to a first aspect of the present invention, a recording layer contains an organic dye and ultrafine particles of silicic anhydride , and the organic dye has the following structural formula (I) or ( II
An optical information recording medium characterized by being an organic dye represented by I) .

Embedded image

According to a second aspect of the present invention, a light reflecting layer, a transparent intermediate layer and a light absorbing layer are sequentially laminated on a transparent substrate,
The light reflecting layer and the light absorbing layer are made of an organic dye thin film, and in an optical information recording medium that forms pits using light of a specific wavelength, the organic dye forming the light reflecting layer has the following structure.
An organic dye represented by Formula (IV) or (VI)
Thus, the organic dye constituting the light absorbing layer has the following structural formula
An organic dye represented by (V), and further comprising the light reflecting layer and
The optical information recording medium is characterized in that both the light absorbing layer and the light absorbing layer contain silicic anhydride .

Embedded image

Hereinafter, the present invention will be described in detail. First, the first invention will be described. The optical information recording medium of the present invention is characterized in that the recording layer contains an organic dye, and ultrafine particles of silicic anhydride.

The ultrafine particles of silicic anhydride in the present invention are:
For example, it is possible to use colloidal silica (methanol silica sol) dispersed in methanol, and the average particle size of the ultrafine silica particles in the dispersion state is preferably 10 to 20 μm. The above-mentioned methanol silica sol and the organic dye are dissolved or dispersed in various organic solvents such as alcohol and used at a concentration suitable for coating.

The content of the ultrafine particles of silicic anhydride in the recording layer is usually 1 to 50 with respect to 100 parts by weight of the organic dye.
Parts by weight, preferably not to desired 5-30 parts by weight. If the amount exceeds 50 parts by weight, the reflectance and recording sensitivity characteristics of an optical information recording medium comprising an organic dye thin film will be reduced.

The organic dyes include cyanine dyes,
Merocyanine dyes, polymethine dyes, azulene, crocones, coroconiums, pyrylium dyes, squarylium dyes, triphenylmethane dyes, anthraquinone dyes, azo dyes, xanthene dyes, and indigoid dyes Can be. An aminium salt / diimonium salt-based compound, a metal chelate complex-based dye, or the like may be appropriately mixed with these dyes in order to enhance the stability to reproduction light and the light resistance.

Further, a binder polymer may be added to the organic dye composition comprising these dyes and ultrafine particles of silicic anhydride to improve coating properties. As the binder polymer, a vinyl chloride resin, a vinyl acetate resin, an acrylic resin, a polycarbonate resin, a polyester resin, a cellulose derivative, a polyethylene resin, a polypropylene resin, a polystyrene resin, or a copolymer or modified resin thereof is used.

The coating method for forming the organic dye thin film is as follows. After dissolving the above organic dye composition in an appropriate solvent, spin coating, dip coating, roll coating, curtain coating, blade coating , Bar coat,
A thin film can be formed by a known method such as gravure coating or knife coating, and the thickness is preferably 300 to 2000 mm. Examples of the substrate used here include glass, resin, and metal.

Next, a configuration example of the optical information recording medium of the present invention will be described with reference to the drawings. As shown in FIG. 1, the optical information recording medium of the present invention basically comprises a substrate 1 provided with a recording layer 2 of a thin film composed of an organic dye composition containing an organic dye and ultrafine particles of silicic anhydride. It is composed of

When the thin film of the recording layer does not contain ultrafine particles of silicic anhydride, the ultrafine particles of silicic anhydride are interposed between the recording layer 2a made of an organic dye thin film and the substrate 1, as shown in FIG. Can be provided. Middle layer 3
Can use the binder polymer described above,
It can be formed by roll coating, bar coating, or spin coating.

Alternatively, as shown in FIG. 3, a protective layer 4 containing ultrafine particles of silicic anhydride may be provided on the recording layer 2a made of an organic dye thin film. Further, although not shown, a layer in which the intermediate layer 3 and the protective layer 4 are used in combination may be used, or a so-called hollow structure in which two recording media having the same configuration are sealed with the recording media facing each other.

The intermediate layer is provided for the purpose of improving the adhesiveness of the recording layer, a barrier against water or gas, and preventing the recording layer from being oxidized. The thickness of the intermediate layer is 0.05 to 2-3 μm
Is preferable. The protective layer has the same structure as that of the intermediate layer, and is provided for the purpose of protecting the recording layer and preventing oxidation and reduction of the recording layer. The thickness of the protective layer is preferably in the range of 1 to 100 μm.

Next, the second invention will be described. The optical information recording medium of the present invention has a light reflection layer, a transparent intermediate layer, and an organic dye having a large absorption for recording / reproducing light, on a transparent substrate, made of an organic dye having no reflection at a recording wavelength and having high reflectance. An optical information recording medium comprising a light absorbing layer comprising a light absorbing layer and a light reflecting layer and a light absorbing layer.
And the transparent intermediate layer contains anhydrous silicic acid.
It is characterized in that it may go out.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 4 is a schematic view showing an example of the optical information recording medium of the present invention, in which 11 is a transparent substrate, 12 is a light reflecting layer,
Is a transparent intermediate layer, 14 is a light absorbing layer, and 15 is a back substrate.

As shown in FIG. 5, the peak of the reflectance of the recording medium is generally on the long wavelength side of the absorption peak. Therefore, when the reflectance is maximized, the absorption decreases and the sensitivity decreases. Occurs. The present invention separates the two functions of light reflection and light absorption in such a recording medium, thereby achieving high reflectance without lowering the sensitivity.

That is, the 12 light reflection layers in FIG. 4 have such a property that the absorption peak is on the low wavelength side of the recording / reproducing light, and the reflectance is high but there is almost no absorption. The 14 light absorption layers have their absorption peaks near the wavelength of the recording / reproducing light. That is, for the wavelength λ of the recording / reproducing light,
Maximum absorption wavelengths λ ^ref _max , λ ^abs _{max of} light reflection layer and light absorption layer
Must have the following relationship:

[0029]

Λ ≧ λ ^abs _max > λ ^ref _max The transparent intermediate layer has a role of increasing the reflectance by the effect of interference as shown in FIG. Therefore, the thickness d ^int of the transparent intermediate layer depends on its refractive index.

[0030]

N ^int = n ^int -ik ^int (where n represents a refractive index and k represents an extinction coefficient) (however,
(Since the transparent intermediate layer has almost no absorption, k ^int = 0)
By

[0031]

(Equation 6) It becomes the maximum when

Similarly, the thickness d ^ref of the light reflecting layer
Also its refractive index

[0033]

[Mathematical formula-see original document] N ^ref = n ^ref -ik ^ref

[0034]

(Equation 8) It becomes the maximum when

From these, the respective thicknesses d ^ref and d ^int of the light reflecting layer and the transparent intermediate layer are set as ^follows .

[0036]

(Equation 9) Then, a medium having a high reflectance can be obtained.

The thickness d ^abs of the light absorbing layer at this time is also

[0038]

(Equation 10) (However, the refractive index of the light absorbing layer

[0039]

[Equation 11] ) Maximizes the reflectance, but the d ^abs dependence of the reflectance is actually small. However, considering the amount of light absorption, if the thickness is too small, the amount of light absorption will be lost.

[0040]

(Equation 12) It is preferable that this is the case.

When the optical recording medium is irradiated with a laser beam having a recording power, a part of the light transmitted through the light reflecting layer and the transparent intermediate layer is absorbed by the light absorbing layer. The light absorbed here is converted to heat and heats the light absorbing layer. At the same time, the heat also heats the light reflection layer via the transparent intermediate layer. The heat forms pits in both the light absorbing layer and the light reflecting layer.
As described above, since the pits are formed not only in the absorption layer but also in the light reflection layer, it is possible to perform recording with a higher recording contrast than the conventional dye single layer type.

Also, at the time of reproduction in which weak light of about 1/10 of the time of recording is applied, the light reflecting layer has almost no absorption, and the amount of absorption in the light absorbing layer is smaller than when there is no light reflecting layer. Therefore, the problem of reproduction light deterioration can be solved.

In the present invention, the ultra-fine particles of silicic anhydride contained in at least one of the light reflecting layer 12, the transparent intermediate layer 13, and the light absorbing layer 14 are, for example, colloidal silica (methanol silica sol) or methanol-dispersed colloidal silica. It is composed of dispersed colloidal silica, and the average particle diameter of the ultrafine silica silicic acid particles in the dispersion state is 10 to 20.
mμ is preferred. For the light reflecting layer and the light absorbing layer, the above-mentioned methanol silica sol and the organic dye are dissolved and dispersed in various organic solvents such as alcohol, and used at a concentration suitable for coating.

The transparent intermediate layer includes a light reflecting layer containing a polymer and methanol silica sol or water-dispersed colloidal silica as an organic pigment as a main component, and a solvent (water, aliphatic hydrocarbon, aromatic hydrocarbon) which does not soak the light absorbing layer. Etc.) and used as a concentration suitable for coating.

The content of the ultrafine silica particles in the light reflection layer and the light absorption layer is usually based on 100 parts by weight of the organic dye when the ultrafine silica particles are not contained in the transparent intermediate layer. 1-50 parts by weight, preferably not to desired 5-30 parts by weight. If the amount exceeds 50 parts by weight, the reflectance is reduced in the light reflecting layer, and the recording sensitivity characteristics are reduced in the light absorbing layer.

When ultrafine particles of silicic anhydride are contained in the transparent intermediate layer, ultrafine particles of silicic anhydride may not necessarily be contained in the light reflecting layer and the light absorbing layer. Is more desirable.

The content of the ultrafine particles of silicic anhydride in the transparent intermediate layer is usually 1 to 5 with respect to 100 parts by weight of the polymer.
0 parts by weight, preferably 5 to 30 parts by weight. If the amount is less than 1 part by weight, the effect of preventing reduction deterioration cannot be exhibited.
If the amount exceeds 0 parts by weight, the film forming property and adhesive property of the transparent intermediate layer deteriorate. It is not always necessary to include ultrafine silica particles in the transparent intermediate layer when the light reflection layer and the light absorption layer include ultrafine silica particles.

The organic dyes used in the light reflecting layer and the light absorbing layer include cyanine dyes, merocyanine dyes, polymethine dyes, azulene, crocones, croconiums,
Examples include pyrylium-based dyes, squarylium-based dyes, triphenylmethane-based dyes, anthraquinone-based dyes, azo-based, xanthene-based, and indigoid-based dyes.

From the properties such as λ _{max of} these dye thin films,
What is necessary is just to select suitably as a light reflection layer and a light absorption layer. Also,
These dyes may be appropriately mixed with an aminium salt / diimonium salt-based compound, a metal chelate complex-based dye, or the like, in order to enhance the stability and light resistance to reproduction light.

Further, a binder polymer may be added to the organic dye composition comprising these organic dyes and ultrafine particles of silicic anhydride to improve coating properties. As the binder polymer, a vinyl chloride resin, a vinyl acetate resin, an acrylic resin, a polycarbonate resin, a polyester resin, a cellulose derivative, a polyethylene resin, a polypropylene resin, a polystyrene resin, or a copolymer or modified resin thereof is used.

The method for applying the organic dye thin film for forming the light reflecting layer and the light absorbing layer is as follows. After dissolving the above organic dye composition in an appropriate solvent, spin coating, dip coating, It can be formed into a thin film by a known method such as roll coating, curtain coating, blade coating, bar coating, gravure coating, knife coating, and the like.
Å2000 ° is preferred.

The transparent intermediate layer is transparent to the laser beam used and has a desired thickness.

[0053]

(Equation 13)

Any material can be used as long as it can form a film, for example, polyvinyl alcohol, polyvinyl acetal, polyurethane, polyamide, polystyrene, cellulose derivative, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, polyolefin and copolymers thereof. Examples include polymers, polycarbonates, acrylic resins, silicone resins, polyesters, petroleum resins, polyparaxylylene, and the like. When the light reflecting layer and the light absorbing layer contain ultra-fine silica particles in addition to the above-mentioned various coatings, the film forming methods include vapor deposition, plasma polymerization, and CVD.

The transparent substrate used in the present invention only needs to be transparent to laser light. For example, polycarbonate, acrylic resin, polyolefin, polyester,
Plastic such as epoxy resin, polyamide, and polyimide, glass, and the like are used. In addition, guide grooves and guide pits for tracking, preformat signals such as address signals are formed on the surface of the transparent substrate, but may be formed directly on the plastic, glass, or the like, or provided on the substrate. May be formed on a light-cured resin.

[0056]

The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention.

Embodiment 1

[0058]

Embedded image

100 parts by weight of the polymethine dye represented by the above formula (I) is added to and dissolved in diacetone alcohol.
Further, methanol silica sol (manufactured by Nissan Chemical Industries, silica solid concentration: 30 wt%, particle diameter: 10 to 20 μm) was added so that the weight of ultrafine silica particles became 10 parts by weight, and a 5% by weight solution of diacetone alcohol was added. It was adjusted to become. The solution was spin-coated on a polycarbonate substrate having a thickness of 0.4 mm, and dried to form a recording layer having a thickness of 900 ° made of an organic dye and ultrafine particles of silicic anhydride.

After laminating with a 0.3 mm-thick polycarbonate resin via a thermoplastic adhesive (ethylene-vinyl acetate copolymer) and thermocompression bonding through a hot roll having a surface temperature of 120 ° C., the card is bonded. An optical card was prepared by punching out the shape.

The initial reflectance of the optical card and the recording contrast with a semiconductor laser (wavelength 830 mm, recording power 3.5 mW, spot diameter 3 μmφ, pulse width 50 μsec)

[0062]

[Equation 14] Was measured.

Further, under the conditions of 65 ° C. and 85% RH,
The reflectance and the recording contrast were measured after standing for 000 hours to perform an environmental storage stability test. Table 1 shows the results
Shown in

Embodiment 2

[0065]

Embedded image

[0066]

Embedded image

100 parts by weight of the polymethine dye represented by the above formula (I) and 30 parts by weight of an aminium salt compound represented by the formula (II) as a light stabilizer were dissolved in diacetone alcohol, and further dissolved in methanol. Silica sol (manufactured by Nissan Chemical Industries, silica solids concentration 30 wt%, particle diameter 10-20 μm) was changed to silica silicic acid ultrafine particles having a weight of 10
5 parts by weight of diacetone alcohol
It was adjusted to be a solution by weight. The solution was added to a thickness of 0.
A 4 mm polycarbonate substrate was spin-coated and dried to form a recording layer made of organic dyes and ultrafine particles of silicic anhydride having a thickness of 1000 °. Hereinafter, the same processing as in Example 1 was performed to prepare an optical card, and the same evaluation as in Example 1 was performed. Table 1 shows the results. Example 3

[0068]

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5 parts by weight of a polymethyl methacrylate resin, 10 parts of a cyanine dye represented by the above formula (III)
0 parts by weight were dissolved in dichloroethane, and methanol silica sol (manufactured by Nissan Chemical Industries, silica solid concentration 30 wt%,
(Particle diameter: 10 to 20 μm) was added so that the weight of the ultrafine particles of silicic anhydride became 10 parts by weight, so that a 3% by weight solution of dichloroethane was prepared. A photocurable modified acrylate resin photocurable film having a thickness of 10 μm was formed on a polycarbonate substrate having a thickness of 0.4 mm, and the above solution was applied by a bar coater, dried, and recorded at a thickness of 1000 mm. A layer was formed. Thereafter, the same processing as in Example 1 was performed to manufacture an optical card, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

Comparative Example 1 An optical card was produced in the same manner as in Example 1 except that no methanol silica sol was used, and the same evaluation as in Example 1 was performed. Table 1 shows the results.

Comparative Example 2 An optical card was prepared in exactly the same manner as in Example 2 except that no methanol silica sol was used, and the same evaluation as in Example 2 was performed. Table 1 shows the results.

Comparative Example 3 An optical card was produced in the same manner as in Example 3 except that the methanol silica sol was not used, and the same evaluation as in Example 3 was performed. Table 1 shows the results.

[0073]

[Table 1] Example 4 As a light reflecting layer, 100 parts by weight of a polymethine dye represented by the formula (IV) was used.

[0074]

Embedded image

The resultant was dissolved in diacetone alcohol and further dissolved in methanol silica sol (manufactured by Nissan Chemical Industries, silica solid content: 30 wt%, particle size: 10 to 20 μm) so that the weight of the ultrafine silica particles became 10 parts by weight. Add
It was adjusted to be a 5.5% by weight solution of diacetone alcohol. The solution was 130 mm in diameter and 1.2 mm in thickness.
The substrate was spin-coated on a substrate having a guide groove (guide grooves of 16 μm pitch, depth of 900 °), and dried to form a light reflecting layer made of an organic dye and ultrafine particles of silicic anhydride having a thickness of 1000 °.

Further, a silicone resin (SD4570, manufactured by Shin-Etsu Silicone Co., Ltd.) was used as a 2% by weight solution of n-hexane on the substrate, and the solution was dropped on the light reflecting layer and spin-coated to form a transparent intermediate layer having a thickness of 1500 mm. The layer was deposited.

Next, a polymethine represented by the following formula (V) was used as the light absorbing layer.

[0078]

Embedded image

100 parts by weight of a dye was added to and dissolved in diacetone alcohol, and methanol silica sol (manufactured by Nissan Chemical Industries, silica solid content: 30 wt%, particle size: 10 to 10 wt.
20mμ) was added so that the weight of the ultrafine particles of silicic anhydride would be 10 parts by weight, and adjusted to be a 5.5% by weight solution of diacetone alcohol. This solution is 130 mm in diameter ,
A 1.2 mm-thick polycarbonate back substrate was spin-coated and dried to form a light-absorbing layer having a thickness of 900 mm and made of organic fine particles and ultrafine particles of silicic anhydride.

Next, the two polycarbonate substrates and the back substrate were pressure-bonded, and the inner and outer peripheral portions were bonded using an ultraviolet-curing adhesive (KRX-650, manufactured by Asahi Denka).
An optical disk was manufactured.

The initial reflectivity of the optical disc and the recording contrast with a semiconductor laser (wavelength 830 mm, recording power 8 mW, spot diameter 1.6 μm, linear velocity 5.6 m / sec, recording pulse width 0.2 μsec)

[0082]

(Equation 15)

Then, the C / N ratio was measured by spectral analysis of the reproduced waveform (scanning filter bandwidth: 30 KHz). Further, the reflectance, the recording contrast, and the C / N ratio were measured after an environmental storage stability test was conducted by leaving the device under a condition of 65 ° C. and 85% RH for 2000 hours. Table 1 shows the results.

Comparative Example 4 An optical disk was produced in exactly the same manner as in Example 4 except that methanol silica sol was not used for the light reflecting layer and the light absorbing layer, and the same evaluation as in Example 4 was performed. Table 1 also shows the reflectance at 830 nm and the position of the absorption maximum of the organic dye alone used in the light reflecting layer (structural formula (IV)) and the light absorbing layer (structural formula (V)).

[0085]

[Table 2]

Example 5 100 parts by weight of an azulene dye represented by the following formula (VI) was used as a light reflecting layer.

[0087]

Embedded image

In addition to dissolving in dichloroethane, methanol silica sol (manufactured by Nissan Chemical Industries, silica solid content: 30 wt%, particle size: 10 to 20 μm) was added so that the weight of the ultrafine silica particles became 10 parts by weight. And adjusted to a 2% by weight solution of dichloroethane.
A cured film of a photocurable modified acrylate resin (thickness: 10 μm, guide groove pitch: 12 μm, guide groove depth: 2500 °) was formed on an acrylic substrate having a thickness of 2 mm, and the above solution was spin-coated and dried to a thickness of 1000 °. Was formed.

Next, as a light absorbing layer, 100 parts by weight of a polymethine dye represented by the formula (V) was added to and dissolved in diacetone alcohol, and methanol silica sol (manufactured by Nissan Chemical Industries, silica solid concentration 30 wt%, particles Diameter 10
-20 mμ) was added so that the weight of the ultrafine particles of silicic anhydride would be 10 parts by weight, and adjusted to be a 5.5% by weight solution of diacetone alcohol, and spin-coated on a PET film having a thickness of 50 μm. After drying, a light-absorbing layer having a thickness of 900 ° and comprising ultrafine particles of an organic dye and silicic anhydride was formed.

Further, an aqueous dispersion of colloidal silica (manufactured by Nissan Chemical Industries, Ltd.) was used as a transparent intermediate layer so that 100 parts by weight of polyvinyl alcohol (manufactured by Kuraray, PVA205) and 10 parts by weight of ultrafine silica particles were added. , Snowtex-0, silica solid content concentration 20wt%, particle size 1
Then, water was added to make a 3% by weight aqueous solution, spin-coated, and dried to form a transparent intermediate layer having a thickness of 1400 ° and comprising ultrafine particles of a polymer and silicic anhydride.

After these acrylic substrates and PET film were superposed, they were superposed on a 0.25 mm thick acrylic back substrate via a 50 μm-thick thermoplastic adhesive (ethylene-vinyl acetate copolymer). After bonding by thermocompression bonding through a hot roll at a temperature of 120 ° C., laser cutting was performed into a card shape to produce an optical card.

The initial reflectivity of the optical card was measured using a semiconductor laser (wavelength 830 mm, recording power 3.5 mW, spot diameter 3 μm, linear velocity 60 mm / sec, recording pulse width 60 μm).
sec), the recording contrast was measured. further,
The reflectance and the recording contrast were measured after an environmental preservation stability test was conducted by leaving the device under a condition of 65 ° C. and 85% RH for 2000 hours. Table 2 shows the results.

Comparative Example 5 An optical card was prepared in exactly the same manner as in Example 5 except that the methanol silica sol of the light reflecting layer and the light absorbing layer was not used, and that the water dispersion cocoa silica was not used in the transparent intermediate layer.
The same evaluation as in Example 5 was performed. Table 3 also shows the reflectance at 830 mm and the position of the absorption maximum of the organic dye alone used in the light reflecting layer (structural formula (VI)) and the light absorbing layer (structural formula (V)).

[0094]

[Table 3]

[0095]

As it has been described above, according to the present invention, Ri by the the use of a recording layer containing a ultrafine particles of an organic-based pigment and anhydrous silicic acid, to prevent lowering of the contrast and reflectivity, An optical information recording medium having good environmental storage stability can be provided.

Further, according to the present invention, an organic light reflecting layer having no reflectance and high reflectance, a transparent intermediate layer, and a light absorbing layer having a large absorption for recording / reproducing light are sequentially laminated on a substrate. By using an optical information recording medium containing ultra-fine particles of silicic anhydride in at least one layer of each layer, high reflectivity, high recording contrast, high C / N ratio, low cost and durable and stable A good optical information recording medium can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an optical recording medium of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of the optical recording medium of the present invention.

FIG. 3 is a schematic configuration diagram illustrating an example of an optical recording medium of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of an optical recording medium of the present invention.

FIG. 5 is a diagram illustrating the wavelength dependence of absorption and reflection in a recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2, 2a Recording layer 3 Intermediate layer 4 Protective layer 11 Transparent substrate 12 Light reflection layer 13 Transparent intermediate layer 14 Light absorption layer 15 Back substrate

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoe Mihara 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hiroyuki Suga 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-62-70834 (JP, A) JP-A-63-85623 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 7/24

Claims (7)

(57) [Claims] An organic dye and ultrafine particles of silicic anhydride are contained in a recording layer, and the organic dye is represented by the following structural formula (I) or
An optical information recording medium, which is an organic dye represented by (III) . Embedded image 2. The optical information recording medium according to claim 1, wherein the recording layer contains 1 to 50 parts by weight of ultrafine particles of silicic anhydride based on 100 parts by weight of the organic dye. 3. A light-reflecting layer, a transparent intermediate layer and a light-absorbing layer are sequentially laminated on a transparent substrate, wherein the light-reflective layer and the light-absorbing layer are made of an organic dye thin film and use light of a specific wavelength. in the optical information recording medium to form pits Te, light reflection
The organic dye constituting the layer is represented by the following structural formula (IV) or
An organic dye represented by (VI), wherein the light absorbing layer is
The organic dye constituting the organic dye is represented by the following structural formula (V).
And the light reflecting layer and the light absorbing layer are both
An optical information recording medium containing silicic anhydride . Embedded image 4. Ultrafine particles of silicic anhydride are added in an amount of 1 to 100 parts by weight of an organic dye constituting a light reflection layer and a light absorption layer.
4. The optical information recording medium according to claim 3, containing 50 parts by weight. 5. The maximum absorption wavelength λ of the light reflecting layer and the light absorbing layer.
^ref _max and λ ^abs _max are given by: 4. The optical information recording medium according to claim 3, wherein: 6. An absorptance of recording / reproducing light in the light reflecting layer is 20% or less, and an absorptivity in the transparent intermediate layer is 5% or less.
4. The optical information recording medium according to claim 3, wherein the optical information recording medium has an absorptance of 50% or more. 7. Thicknesses d ^ref , d ^{int of the} light reflecting layer and the transparent intermediate layer
Is the refractive index of (Where n represents the refractive index and k represents the extinction coefficient). 4. The optical information recording medium according to claim 3, wherein